GB2614964A - Method of assembling a firearm - Google Patents

Abstract

A component of a firearm, such as a shotgun or rifle, comprises a first barrel 301 and a top rib 305. The first barrel 301 has one or more first interlocking features. The top rib 305 has one or more second interlocking features. The top rib 305 is secured to the first barrel 301 by engagement of one or more of the first interlocking features with the one or more second interlocking features.

Description

METHOD OF ASSEMBLING A FIREARM

TECHNICAL FIELD

The present invention relates to a method of assembling, manufacturing or repairing a component of a firearm, a component of a firearm and a firearm.

BACKGROUND

Firearms are well known. A firearm is a gun (i.e. a barreled ranged weapon) which is designed to be carried and fired by a single individual. A firearm inflicts damage upon a target by launching one or more projectiles which are driven by rapidly expanding high-pressure gas produced by exothermic combustion (deflagration) of a chemical propellant. If gas pressurisation is achieved through mechanical gas compression rather than through chemical propellant combustion then the gun is commonly referred to as an air gun rather than a firearm. Broadly speaking, firearms as owned by civilians for sporting or land management purposes typically fall into two categories namely: (i) rifles; and (ii) shotguns.

A rifle is a single-person portable long barreled firearm which is designed for accurate shooting of a target at distance. Importantly, a rifle is distinguished by having a barrel which has a helical pattern of grooves (rifling) which are cut into the bore wall. As will be explained in more detail below, the effect of the rifling is to impart spin upon a projectile (bullet) as the projectile is discharged from the rifle. The impartation of spin upon the bullet stabilises the flight of the bullet enabling a high degree of accuracy to be obtained.

A shotgun is a firearm that is usually designed to be fired from the shoulder. Instead of firing a bullet, a shotgun fires a number of small pellets. The pellets are initially housed in a cartridge. A charge in the base of the cartridge is detonated and the resulting release of energy causes the plurality of small spherical pellets (commonly referred to as shot) to be ejected. It is also known for shotguns to eject a solid projectile called a slug.

Shotguns come in a wide variety of sizes, ranging from 5.5 mm (.22 ") bore up to 5 cm (2.0 ") bore. Furthermore, known shotguns have numerous different types of operating mechanisms. For example, known shotguns include breech loading, single barreled, double barreled, pump-action, bolt-action and lever-action variants.

The ownership and use of both air guns and firearms (such as rifles and shotguns) is tightly regulated in most countries around the world for obvious reasons. In the UK the ownership of a rifle requires a Firearms Certificate (FAC) and the ownership of a shotgun requires either a Shotgun Licence or a Firearms Certificate.

The method of assembling a firearm according to the present invention is particularly advantageous from an environmental perspective in that: (i) a firearm when assembled according to the present invention is particularly suited for firing steel rather than lead shot; (ii) the method of assembling a firearm according to the present invention avoids any need to solder two ribs to two barrels of a double barreled shotgun thereby avoiding the use of environmentally harmful fin solder; and (iii) the method of assembling a firearm according to the present invention enables an assembled firearm to be blackened or otherwise provided with a final colouring without needing to use conventional chemicals to blacken or otherwise colour an assembled firearm. It will be apparent, therefore, that the method of assembling a firearm according to the present invention is particularly environmentally friendly.

Sporting firearms divide into two groups -shotguns which have smooth bored barrels and fire a quantity of small metallic pellets and rifles which fire a single projectile through a rifled and helically grooved barrel. Both types of sporting firearms fire cartridges which consist of a cylindrical case (cartridge) containing a projectile, either a bullet (rifle) or shot pellets and wadding (shotgun) and a propellant powder. The powder is ignited by a cap or primer in the base of the case (cartridge) and provides a high-pressure gas which acts as an accelerant to accelerate the projectile along the barrel of the firearm from a proximal end of the barrel to a distal end of the firearm known as the muzzle. The projectile then exits the firearm via the distal end of the barrel and continues on a trajectory towards the intended target.

Shotguns normally have two barrels. One variant of a shotgun is known as an over-under (0/U) shotgun and has the two barrels arranged vertically so that a first barrel is arranged above a second barrel. Another variant of a shogun is referred to as a sideby-side (S/S) shotgun and has the two barrels arranged horizontally so that a first barrel is arranged alongside a second barrel. Shotguns fire an expanding cloud of pellets which typically have an effective range of 40-50 m. The quantity of pellets, known as shot, normally weighs 25-35 g in total and typically numbers a few hundred per cartridge.

The shot diameter and material may vary for different uses. The pellets are designed for shooting moving targets, usually flying, and are widely used for live game bird shooting, pest control and clay target shooting. Traditionally, shot has comprised lead shot but increasingly, for environmental reasons, there is a move away from lead shot to steel shot. Clay target shooting has become a popular sport and there are several Olympic disciplines.

Although most rifles are single barreled, double barreled rifles are known in both 0/U and S/S configurations similar to shotguns. Unlike shotguns, rifles fire a single projectile or bullet. The projectile or bullet normally makes an interference fit in a grooved helical inner bore of the rifle barrel with the result that the projectile or bullet is effectively guided and spun as the projectile or bullet passes through the length of the barrel.

It will be understood by those skilled in the art that the effect of the rifling upon the projectile or bullet is to impart spin upon the projectile or bullet which acts to stabilise the projectile or bullet in flight. The impartation of spin upon the projectile or bullet stops the projectile or bullet from wobbling or tumbling and gives the projectile or bullet a greater accuracy at long range. Rifles are commonly used for shooting all types of terrestrial game animals, pest control and target shooting. Target rifle shooting has long been a popular sport and is included in several Olympic events. Rifles vary in range from 30-50 m for small bore to >1000 m for full bore high velocity rifles.

The performance of sporting firearms can be measured in several ways. Firstly, accuracy is a measure of how well a rifle or shotgun shoots to the point of aim. For double barreled shot guns and rifles the construction and alignment of the barrels is critical. Secondly, reliability is a measure of consistent operation of the parts of a rifle or shotgun in use over time. Thirdly, pattern control is (for shotguns) a measure of the quality and density of a pattern of pellets at various distances achieved through the conformation of barrel bores and choked muzzles. Fourthly, handling weight and fit is more commonly a factor with shotguns which can have a relatively wide range of parameters if a shotgun is handmade to order. In particular, it is desirable to manufacture bespoke shotguns which are comfortable for the user and which are suited to the user's style of shooting.

In known manufacturing techniques of double barreled shotguns and rifles, each barrel tube, blank or drawn tube is initially formed separately. For example, each barrel may initially be formed by drilling a single hole through a metal bar or blank. Alternatively, each barrel may be formed by forging. In either scenario, it is common to further finish the barrel bores e.g. by honing in order to achieve a good finish.

Once an internal aperture has been formed within each barrel blank, the outside of each barrel may then be completed by turning the barrel on a lathe. The two barrels for both 0/U and S/S firearms may either: (i) have integral breech sections which are hard soldered together; or OD the two barrels are inserted into a separate breech section, known as a monoblock, and are then soft soldered in place.

In both cases, the result is an assembly where the barrels are connected together for approximately 70 mm at the breech but the rest of the length of the barrels are unconnected to each other at this stage in the manufacturing process.

The arrangement of the barrels is critical to accuracy and the bores should converge from breech to muzzle. This is achieved with careful design and manufacture of the breech sections on the monoblock. The barrels mounted to the monoblock at one end have a relatively large degree of freedom of movement and it will be understood that they need to be connected together over their length in order to form a rigid structure. The known method of connecting the tubes is to use thin metal strips of various sections called ribs which are soft soldered to the tubes along their length. A S/S gun may have a top rib and a bottom rib. An 0/U shotgun may have two side ribs and a top rib to assist aiming.

EP-3159560 (Stewart) discloses a gun barrel manufacturing process. In particular, a method of manufacturing a set of integral gun barrels is disclosed which is achieved by machining a single metal block to form a first and a second gun barrel. This is followed by a step of machining a bore in each of the first and second barrel sections. This, however, results in the first and second gun barrels being substantially parallel to each other.

It will be appreciated, however, that it is undesirable for the two barrels to be parallel with zero convergence. As will be understood by those skilled in the art, convergence of the barrels of a firearm is a desirable characteristic of a firearm, as it is required to compensate for the movement of the gun or rifle under recoil.

In a side-by-side firearm, firing the right barrel will cause the firearm to move slightly to the right and vice versa for the left, so that if the bores were parallel then the shots would diverge. In an over-and-under gun the same is true but in a vertical plane.

For a shotgun, which is firing a spread of pellets, high precision of alignment is much less necessary than in a double rifle where each barrel only fires one projectile. A double rifle therefore requires very careful regulation of the barrel alignment to ensure that both barrels will shoot to point of aim with a particular cartridge and bullet weight.

A problem with known rib forms and fixings is the failure of the soldered joints over time. The joint surfaces are often narrow lines with small contact area because the ribs are made from steel and kept thin to reduce weight. Another known problem, often after repair of failed soldered joints, is that the tubes can be deflected and misaligned due to the difficulty of securing them during the heating and soldering process. Conventional methods of assembling or manufacturing a firearm are particularly time consuming and labour intensive and the overall process is environmentally unfriendly.

It is desired to provide an improved method of assembling or manufacturing a firearm which is less time consuming, less labour intensive and which is more environmentally friendly than conventional methods.

SUMMARY

According to an aspect of the present invention there is provided a method of assembling, manufacturing or repairing a component of a firearm comprising: providing a first barrel having one or more first interlocking features; providing a top rib having one or more second interlocking features; and securing the top rib to the first barrel by engaging the one or more first interlocking features with the one or more second interlocking features.

The present invention is particularly advantageous in that the method of interlocking the top rib to the first barrel provides a secure connection between the two components particularly in the region towards the muzzle where the top rib may have a relatively small cross-sectional profile (since the top rib tapers towards the muzzle end) and since the muzzle end of the barrels is most likely to suffer a knock by a user.

The top rib may additionally be glued to the first barrel so that the combination of an adhesive and a mechanical interlock between the top rib and the first barrel provides are extremely strong interconnection.

Optionally, the step of engaging the one or more first interlocking features with the one or more second interlocking features comprises moving or sliding the one or more first interlocking features relative to the one or more second interlocking features.

Optionally, the one or more first interlocking features comprise one or more projections and the one or more second interlocking features comprise one or more recesses.

Optionally, the one or more first interlocking features comprise one or more recesses and the one or more second interlocking features comprise one or more projections.

Optionally, the one or more recesses have a female dovetail or trapezoidal cross-sectional profile.

Optionally, the one or more projections have a male dovetail or trapezoidal cross-sectional profile.

Optionally, the method further comprises additionally securing the top rib to the first barrel using a liquid adhesive.

Optionally, the liquid adhesive is selected from the group comprising: (i) anaerobic; 00 epoxy 1 and 2 pack; (iii) acrylic 1 and 2 pack; and (iv) polyurethane 1 and 2 pack.

Optionally, the top rib comprises either a non-vented top rib or a vented top rib. Optionally, the first barrel comprises a metal or a metallic alloy.

Optionally, the metal or metallic alloy comprises steel such as 709M40T, CARRSP20, EN19T or EN241.

Optionally, the method further comprises securing the first barrel to a second barrel to form a double barrel assembly.

Optionally, the method further comprises securing one or more inter-ribs or spacing elements between the first barrel and the second barrel.

Optionally, the one or more inter-ribs or spacing elements are secured along at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% of the longitudinal length of either the first barrel and/or the second barrel Optionally, the one or more inter-ribs or spacing elements comprise a metallic alloy or a composite.

Optionally, the metallic alloy is selected from the group consisting of: (i) an aluminium alloy; (ii) a titanium alloy; and (N) a magnesium alloy.

Optionally, the composite comprises a carbon fibre or glass fibre composite.

Optionally, one or more sacrificial sections are used to hold the one or more inter-ribs or spacing elements during manufacture and wherein optionally the one or more sacrificial sections may be removed or machined off post-manufacture.

Optionally, the firearm further comprises a monoblock and the method further comprises the step of securing a first end of the first barrel to the monoblock using laser welding, electron beam welding or gluing and/or securing a first end of a second barrel to the monoblock using laser welding, electron beam welding or gluing.

Optionally, the step of securing the first end of the first barrel to the monoblock using laser welding, electron beam welding or gluing and/or securing a first end of the second barrel to the monoblock using laser welding, electron beam welding or gluing is performed prior to and/or subsequent to the step of securing one or more inter-ribs or spacing elements between at least the first barrel and the second barrel using a liquid adhesive.

Optionally, the step of securing the first end of the first barrel to the monoblock using laser welding, electron beam welding or gluing and/or securing a first end of the second barrel to the monoblock using laser welding, electron beam welding or gluing is performed prior to and/or subsequent to the step of securing the top rib to the first barrel.

Optionally, the first barrel and the second barrel are secured in the monoblock so as to be angularly converging at an angle < 1° relative to each other.

According to another aspect there is provided a component of a firearm comprising: a first barrel having a first interlocking feature; and a top rib having a second interlocking feature; wherein the top rib is secure to the first barrel by engagement of the first interlocking feature with the second interlocking feature.

According to another aspect there is provided a firearm comprising a component as described above.

Optionally, the firearm comprises a double barreled shotgun, wherein the first barrel and the second barrel of the shotgun are arranged in an over-under (0/U) arrangement or a side-by-side (S/S) arrangement.

According to another aspect there is provided a method of assembling, manufacturing or repairing a component of a firearm comprising the steps of: (a) securing one or more inter-ribs or spacing elements between a first barrel and a second barrel using a liquid adhesive; (b) attaching one or more first interlocking features to the first barrel and providing a top rib having one or more second interlocking features; (c) securing the top rib to the first barrel by engaging the one or more first interlocking features with the one or more second interlocking features; and (d) laser welding, electron beam welding or gluing the first and second barrels to a 35 monoblock.

Optionally, the method further comprises performing step (a) before or after step (b).

Optionally, the method further comprises performing step (a) before or after step (c).

The method of assembling, manufacturing or repairing a component of a firearm may further comprise securing one or more inter-ribs or spacing elements between at least a first barrel and a second barrel using a liquid adhesive. Use of a liquid adhesive to secure an inter-rib or spacing element between two barrels of a firearm renders the use of two metal ribs redundant. Furthermore, gluing the two barrels to an inter-rib is a significantly simpler process than soldering two ribs to the barrels to join them and then removing any excess solder. Any excess glue or liquid adhesive can simply be removed by cleaning the portion of the barrel assembly with a solvent. The liquid adhesive may be cured at temperatures which range from room temperature up to a temperature of typically 140°C. Accordingly, the method imparts less thermal energy to the barrels with the result that the barrels are not adversely affected during assembly. The inter-rib may be made from a lightweight material and hence a lighter firearm may be produced if desired.

One or more spacers or packing pieces made from, for example, carbon fiber or other such lightweight materials may be utilised. The one or more spacers or packing pieces may have an overall thickness in the range 1-200 pm. The one or more spacers or packing pieces may be used to ensure that the adhesive does not get materially displaced and that sufficient adhesive remains during the bonding process to ensure a strong adhesion bond between the components. The spacers or packing pieces may be placed at 90° to the top rib or the inter-rib. The spacers or packing pieces may be approx. 30 mm long and may comprise a bundle of 30-50 individual filaments. The spacers or packing pieces may comprise a bundle of individual filaments such that the bundle has a total thickness of approx. 50-80 pm i.e. approximately the same thickness as a human hair.

The use of spacers or packing pieces enables there to be enough adhesive in contact between the top rib or inter-rib and the barrel(s) for an optimal bond to be formed.

In particular, the use of spacers or packing pieces ensures that the adhesive is not squeezed out completely and that a 50-80 pm gap or thickness of adhesive is left within the barrel rib assembly. Filament bundles may be repeatedly laid along the length of the rib/barrel assembly and once an appropriate spacing along the assembly length has been achieved, the barrel(s) and the rib may be clamped together. It will be apparent, therefore, that bundles of spacers or packing pieces may stick out from the rib/barrel assembly but these may be trimmed off with a sharp blade once the adhesive has cured slightly or completely.

The firearm may comprise a single or double barrelled shotgun or a rifle. For example, an embodiment is contemplated wherein a single barrelled shotgun or rifle is provided and wherein a top rib is glued or otherwise attached to the top of the barrel.

Less preferred embodiments are also contemplated wherein a firearm comprising more than two barrels is provided. For example, a firearm having three or four barrels is contemplated. The barrels may comprise a metal or metallic alloy such as steel and in particular type 709M40T, CARRS-P20, EN19T or EN24T steel. The steel may comprise an ordinance quality steel having around 0.4%wt carbon, 1%wt manganese, 0.25%wt molybdenum, 1%wt chromium and optionally trace amounts of phosphorus and sulphur.

The metal or metallic alloy may comprise a higher grade ordinance steel comprising carbon at 0.5crowt or similar steels of equivalent composition. For example, a steel alloy may be utilised which comprises a Cr-Mo alloyed steel supplied in a hardened and tempered condition.

One or both barrels of the shotgun, rifle or firearm may be fabricated from a superalloy. A superalloy, or high performance alloy, is an alloy that exhibits excellent mechanical strength and creep resistance at high temperatures, good surface stability, and corrosion and oxidation resistance. Superalloys typically have an austenitic face-centred cubic crystal structure with a base alloying element of nickel, cobalt or nickel-iron.

The superalloy may comprise a nickel-based superalloy which contains one or more alloying elements such as chromium (Cr), aluminum (Al), titanium (Ti), molybdenum (Mo), tungsten (VV), niobium (Nb), tantalum (Ta) and cobalt (Co).

Steel makers offer special ordnance-grade steel alloys for the manufacture of gun barrels. Ordnance-grade alloys are subjected to special handling, careful heat treatment and rigorous analysis to assure quality and consistency. The barrels may be monolithic -that is, the entire barrel is made out of a single piece of metal. The steel barrels may have a hardness of around 25 to 32 on the Rockwell C scale. Suitable metal alloys for monolithic gun barrels include: (i) alloy steels; (ii) stainless steels; (iii) columbium; and (iv) aluminium.

Suitable barrel alloys include types having varying amounts of chromium, molybdenum, vanadium, nickel and manganese as alloying metals. For example, SAE 4140 chrome-molybdenum (chrome-moly) steel if often used in the US whereas in Europe vanadium and nickel-steel alloys are preferred. Most standard barrels are made with alloy steels as they offer an excellent balance of strength and cost.

Stainless-steel barrels are known but are significantly less common than alloy steels. Stainless steel typically has a better resistance to heat erosion compared with chrome-moly barrels. Stainless steel also has an improved resistance to rust and nearly eliminates corrosion in humid environments. Stainless steel barrels have become a popular choice for competition rifles, varmint rifles, all-weather rifles, combat handguns and marine shotguns. An especially popular stainless steel alloy used by several barrel makers is type 416R stainless steel. Like all stainless steels, it contains a high percentage of chromium (approx. 10%) and small amounts of sulphur to make it easier to machine.

-10 -Barrels made of stainless steel are more expensive than those made of alloy steel, as the cost of the raw materials is higher. Columbium is an elemental metal with similar physical and strength characteristics to stainless steel, but with superior resistance to heat erosion and corrosion. However, columbium is scarce and very expensive, making it a rare choice for a gun barrel. Aluminum is very light, but it lacks the strength and resistance to heat erosion found in steels. For this reason, aluminum barrels must have a steel liner. Aluminum-alloy sleeves around a steel barrel are common in revolvers such as the DAN WESSON (RTM) series.

Titanium-cobalt alloys offer the strength of steel at approximately half the weight.

However, titanium is very expensive and difficult to machine. In addition, titanium barrels and cylinders require a steel liner. Popular applications include barrels, cylinders on some models of SMITH & WESSON (RTM) and TAURUS (RTM) revolvers, as well as some models of bolt-action rifles, notably recent models from REMINGTON (RTM).

It is known to measure the surface hardness of a material using a Vickers hardness test. The result of a Vickers hardness test is conventionally reported as a Vickers hardness number in the form)ood-IVyy e.g. 440HV30 or xxxl-IVyy/zz if duration of force differs from 10-15s e.g. 440HV30/20, wherein 440 is the hardness number, HV gives the hardness scale (Vickers), 30 indicates the load used in kgf and 20 indicates the loading time if it differs from 10-15 s. Conventionally, the type of steel used to fabricate shotgun barrels has to be able to withstand pressures up to approximately 20,000 psi. Furthermore, as will be understood by those skilled in the art, rifles typically have to be able to withstand even higher pressures typically in excess of 50,000 psi. Chrome-molybdenum steel alloys are designated by grades such as AISI 4140, AISI 4150 and AISI 4340 in the US. The British equivalent of these steels is EN 19 and EN 24. These steels are generally used for military grade firearms as well as hunting rifles.

The other type of steel is a stainless steel alloy such as 416 type stainless steel.

This is not a true fully austenitic stainless steel such as the types used in making cutlery items such as knives and forks. 416 type stainless steel is a martensific steel which can be hardened by heat treating, similar to carbon steel. It is more accurately a high chrome content (> 10%) steel having enough sulphur to give it good machining properties. This steel is generally used by target shooters and is considered to be easier to machine accurately than chrome-moly steels. It is also more expensive than chrome-moly steel, has a shorter life and is more difficult to black. Hence, military and hunting rifles may comprise chrome-moly steel while target shooters may prefer stainless steel.

Whatever the type of steel chosen, the most important characteristics of the steel are ease of machining, longevity and strength. Other considerations are resistance to corrosion and ability to be blackened.

It is important for these steels to have high tensile strength i.e. resistance to being pulled apart. These steels can easily withstand over 100,000 psi which is significantly greater than the maximum expected pressure (20,000 psi for shotguns and 50,000 psi for rifles). Hardening steels generally increases tensile strength, but it also tends to make the steel brittle and susceptible to hard knocks. Accordingly, these steels must also withstand shock. A tradeoff is made between tensile strength and impact strength and therefore, the barrels are typically hardened to between 255HV and 303HV.

The steel for the barrels is generally not made by the barrel makers themselves, but instead arrives from external vendors in lengths of 5.0-7.5 m long cylindrical bars with a diameter dependent upon the barrel makers specifications. For example, barrels intended for hunting rifles may have a diameter of 3.25 cm and barrels for smaller.22 rifles may be 2.5 cm in diameter. The external vendor generally stress-relieves the steel bars before delivery. The steel may already been tempered at 600 °C and the hardness of the steel may have been reduced. The first step of the process is to cut the bars to the required length of gun barrels. It will be understood that the finished length of a shotgun is typically 28-34" and that the finished length of a rifle is typically 20-25". Once the barrel blank has been cut to size a hole is typically drilled into the barrel blank. The barrel bore is then typically further finished i.e. by honing after drilling in order to achieve a good finish. The steel used for one or both barrels may have a Vickers Hardness number in the range 250-300HV, 300-350HV, 350-400HV, 400-450HV, 450-500HV or > 500HV.

A single inter-rib or spacing element may be secured between the first barrel and the second barrel. However other embodiments are contemplated wherein more than one inter-rib or spacing element may be provided. For example, a series of inter-ribs may be provided between two barrels in order to provide a method of air venting the barrels. Traditional shotguns for hunting purposes are typically non-vented and relatively few shots will be fired over a relatively long period of time. However, with clay pigeon shooting a shotgun may be fired repeatedly within a very short period of time with the result that the barrel(s) can quickly get very hot. As a result, it is known to provide a rib which has air gaps provided therein in order to assist in the barrels cooling due to convection.

One or more inter-ribs or spacing elements may be provided comprised of a composite, a metal or a metallic alloy such as an aluminium alloy, a titanium alloy or a magnesium alloy or any other suitable material. According to other embodiments the metallic alloy may comprise a steel alloy. The composite may comprise carbon fibre, graphite, KEVLAR (RTM) or a glass fibre composite.

The one or more inter-ribs or spacing elements may comprise one or more -12 -sacrificial sections or elements or more generally the manufacturing process may include the use of one or more sacrificial sections which is (are) used to hold the inter-rib(s) or spacing element(s) whilst the geometry is being machined. Once finished the sacrificial section(s) or element(s) are preferably removed by being machined off which produces the inter-rib(s) or spacing element(s) in its final form. Less preferably, the one or more sacrificial sections or elements may be removed once the one or more inter-ribs or spacing elements have been secured to the first and second barrels.

According to an embodiment, the two barrels may be angled or inclined towards each other at the distal end by a few degrees. For example, the barrels may be angled or inclined at <0.10, 0.1-0.2°, 0.2-0.3°, 0.3-0.4°, 0.4-0.5°, 0.5-0.6°, 0.6-0.7°, 0.7-0.8°, 0.80.9°, 0.9-1.0° and > 1° off parallel or otherwise inclined towards each other.

According to various embodiments there is provided a component of a firearm comprising at least a first barrel, a second barrel and one or more inter-ribs or spacing elements secured between at least the first barrel and the second barrel using a liquid adhesive. The component may further comprise one or more top ribs secured to one of the first and second barrels using a liquid adhesive. The one or more top ribs may comprise either a non-vented top rib or a vented top rib. The liquid adhesive is preferably selected from the group comprising: (i) anaerobic; (ii) epoxy 1 and 2 pack; (iii) acrylic 1 and 2 pack; and (iv) polyurethane 1 and 2 pack. The liquid adhesive may comprise an Epoxy Weld (RTM) Bonding Weld compound (LOCTITE (RTM)) or any other liquid adhesive with similar bond strength, water resistance, heat resistance and impact resistance properties.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention together with other arrangements given for illustrative purposes will now be described, by way of example only, and with reference to the accompanying drawings in which: Fig. 1 shows a known double barreled shotgun wherein the two barrels are arranged in an over-under (0/U) configuration; Fig. 2 shows a known double barreled shotgun wherein the two barrels are arranged in a side-by-side (S/S) configuration; Fig. 3 shows an exploded view of a shotgun barrel assembly wherein two barrels of a double barreled shotgun are secured to an inter-rib using a liquid adhesive and wherein optionally a top rib is also secured to the upper surface of the upper barrel with a liquid adhesive and wherein both barrels are also either glued and/or laser welded into a -13 -monoblock; Fig. 4 shows an inter-rib wherein the inter-rib acts as a spacer between two barrels of a double barreled shotgun and wherein the two barrels are glued to the inter-rib using a liquid adhesive; Fig. 5 shows a top rib wherein the top rib is preferably glued using a liquid adhesive to the upper barrel of a double barreled 0/U shotgun arrangement; Fig. 6 shows the action of a shotgun for illustrative purposes; Fig. 7 shows a monoblock and two barrels which, in use, are either glued and/or laser welded into the monoblock; Fig. 8 shows a ventilated or skeletonised inter-rib wherein different dimension apertures are optionally provided in the ventilated or skeletonised inter-rib; Fig. 9A show corrosion of a conventional 0/U top rib and Fig. 9B shows corresponding corrosion of a conventional S/S top rib, Fig. 10A illustrates a method of laser welding two barrels into a monoblock according to an embodiment, Fig. 10B shows a weld formed by laser welding to the barrel and Fig. 10C shows the result of polishing; Fig. 11A shows an embodiment wherein a top rib is provided having one or more female dovetail sections for interlocking with one or more male dovetail sections provided on the upper barrel of a double barrel assembly and Fig. 11B shows the top rib interlocked to the upper barrel; Fig. 12 shows in greater detail a female dovetail section provided on a top rib towards the muzzle end and a corresponding male dovetail section provided on the upper barrel of a double barrel assembly; and Fig. 13 shows an embodiment wherein a top rib has been interlocked to the upper barrel of a double barrel assembly, wherein the barrel is shown secured to a monoblock.

DETAILED DESCRIPTION

Various aspects of a conventional shotgun will now be described in more detail in order to explain in general terms the functioning of a shotgun and to illustrate how, conventionally, shotguns are manufactured. A person skilled in the art will appreciate that -14 -conventionally the production of shotguns is a highly skilled and labour intensive activity.

At present (2022) prices a mid-range shotgun may retail in the UK in the price range of 1.20-50k which is indicative of the number of hours of skilled labour which has gone into the production of the shotgun. It will also be understood by those skilled in the art that there has been very little innovation in the field of shotguns for several decades.

Fig. 1 shows a conventional shotgun 100 having a boxlock action 101 which comprises a hammerless action comprising concealed self-cocking hammers in a break-open type action. The side of the boxlock action 101 comprises a hammer block safety (not shown) which is automatically engaged when the hammers are cocked. The shotgun also comprises a trigger mechanism 103. Modern conventional shotguns utilise a single trigger mechanism which is commonly referred to as a single selective trigger (SST). The trigger mechanism 103 is typically arranged to alternately fire both barrels 102 of the shotgun in quick succession. In order for both barrels to be fired, the SST must be pulled twice.

The change from one barrel to the other may be accomplished by use of a clockwork type system wherein a cam alternates between the two barrels 102.

Alternatively, an inertial system may be used wherein the resultant recoil of firing the first barrel may be used to toggle the trigger to the second barrel.

Most modern double barreled shotguns including the double barreled shotgun exemplified in Fig. 1 have, what is commonly known in the art as, a break open action. A break open action means that when the shotgun is opened, the barrels 102 are tilted downwards so as to expose the breech ends of the barrels 102 for unloading and reloading purposes. As will be understood by those skilled in the art, conventional double barreled shotguns are typically provided in two distinct configurations.

According to an arrangement a shotgun may be provided having twin barrels arranged in an over-under (0/U) arrangement as shown in Fig. 1. Alternatively, the twin barrels of the shotgun may be arranged in a side-by-side (S/S) arrangement as shown in Fig. 2. Double barreled shotguns offer a number of advantages over a single barreled shotgun. Most obviously, a second barrel enables a user to get a second shot at the quarry or target. Furthermore, a double barreled shotgun enables a user access to fit each barrel with different chokes. A choke relates to a tapered constriction of a gun barrel 102 at the muzzle (distal) end of the barrel 102. Different chokes result in different performance characteristics e.g. range and accuracy. In this regard, shotgun users may choose to have a different choke fitted to each barrel 102 of a double barreled shotgun.

Conventionally, double barreled shotguns are assembled by forming initially each -15 -barrel tube separately. Each barrel 102 may initially be formed by drilling a single hole through a metal bar or barrel blank. Alternatively, the barrels 102 may be formed by forging. Once an internal aperture has been formed in the barrel blank (and optionally the bore hole honed or otherwise finished) then the outside of the barrel 102 may be formed e.g. by turning the barrel on a lathe. The two barrels for an 0/U or S/S configured shotgun may each have an integral breech section which are then hard soldered together. Alternatively, both barrels may be inserted into a separate monolithic breech section known as a monoblock and the barrels are then soft soldered into position. Both systems result in a barrel assembly wherein the two barrels of the shotgun are connected together for approximately 70 mm at the breech (proximal end) but the rest of the length of the tubes are unconnected at this stage in the production of the shotgun.

The arrangement of tubes is critical to accuracy and the bores should converge from breech (proximal end) to muzzle (distal end). This is achieved with careful design and manufacture of the breech sections on the monoblock.

The tubes or barrels when initially mounted are relatively adjustable and the next step in the process is to solder both barrels together over their length so that the barrels and breech section form a rigid assembly. The known method of connecting the barrels together involves placing two thin metal strips, commonly called ribs, either side of the barrels. The two ribs are then soft soldered to the barrels over their length so that the two barrels become welded together. It will be understood that a side-by-side shotgun will have a first (top) and a second (bottom) rib at the interface between the two barrels. An over-under shotgun will similarly have two ribs (one either side of the barrel assembly).

Furthermore, normally an additional top rib will be welded to the upper barrel of an 0/U shotgun to assist with aiming.

Fig. 2 shows, for illustrative purposes, only a side-by-side boxlock shotgun having side plates. The shotgun comprises two barrels 201. Different sizes of barrel allow for different widths of cartridge, which in turn defines the gun's gauge (i.e. 12 or 20 bore).

The size denomination comes from one pound of lead divided into equal-sized balls which will fit the barrel 201. For example, 12 pieces equals 12 bore and hence a 20 bore shotgun has smaller diameter barrels than a 12 bore shotgun.

The shotgun further comprises extractors 202 which help release a spent cartridge from each of the barrels 201 after the shotgun has been fired. If the shotgun has not been fired but the shotgun is nonetheless opened or "broken" then the extractor 202 will pull the rim of the cartridge out of the barrel 201 making it simpler to remove an unused cartridge. If, however, a shotgun cartridge has been detonated, then the extractors 202 will automatically eject the spent cartridge when the shotgun is "broken" i.e. opened.

-16 -A bolt 203 is provided which holds the barrels shut whilst the cartridge(s) are shot or fired. The bolt 203 is disengaged by a top lever 204 which is arranged to disengage the bolt 203 from the barrels 201 allowing the gun to open. The top lever 204 is then returned home by a top lever spring. When a S/S shotgun is placed in a "safe" position which prevents accidental triggering of the shotgun, a thumb piece 205 locks the trigger 207 and has the effect of stopping the shotgun from firing inadvertently. The safety mechanism on most 0/U shotguns is slightly different and the safety mechanism comprises a safety catch or thumb piece 205 which disengages the mechanism leaving the trigger free to move but not fire.

A trigger guard 206 is provided for the trigger 207 and attaches to the base of a trigger plate 208. When the trigger 207 is pulled a series of mechanical actions are triggered in series within the gun's lockwork. The series of events comprise the trigger 207 releasing a sear and subsequently a hammer. This allows a spring to release which forces the hammer, via a striker, through striker holes in the action body to strike and thus detonate a loaded cartridge. A trigger plate 208 is shown in Fig. 2 which houses the trigger 207. The trigger plate 208 is secured to the action body at one end and sits within the stock of the shotgun at the other end.

A hammer or tumbler 209 is propelled by the main spring within the gun and is not released until the series of events unleashed by pulling the trigger 207 is initiated. The point at which the sear holds the hammer from firing is referred to as 'being in bent'. A main spring applies force to the hammer 209. On classic British shotguns a leaf spring is typically used as opposed to a coil spring. Present day handmade British shotguns are usually manufactured with a leaf spring which is viewed as a sign of high quality. A cocking limb 211 resets the chain reaction of mechanical events which are unleashed when the trigger 207 is pulled. When the shotgun is opened or "broken" the cocking limb 211 is forced down by the fore-end to the point at which the hammer, main spring, sear and trigger are back in their original positions (i.e. in bent). A kicker 212, when released, is sprung by the ejector spring into the extractors to eject the cartridges. The kicker 212 will only release and expel the cartridge if it has been fired. The mechanical process for this is related to the lock mechanism, as the movement of the cocking limb 211 releases the kicker 212. An ejector spring 213, when one or both cartridges have been fired, forces the kicker 212 into the extractors to expel the used or spent cartridge from the barrel(s). The fore-end 214 ensures the barrels 201 are supported into the hook of the action. The fore-end 214 prevents the barrels 201 from pulling off the action body breech face, as the fore-end is secured through a loop on either a Deeley catch or Anson rod and around the action knuckle.

A loop section of the gun 215 is attached to the barrels 201 and in the type of shotgun illustrated by Fig. 2 a Deeley catch holds the fore-end 214 and fore-end wood -17 -onto the barrels 201 as the fore-end pivots around the knuckle of the action. A Deeley catch 216 has three components: (i) a catch case; 00 the catch itself; and (iii) a spring which is arranged to force the catch back into place. The catch is used to attach the fore-end 214 onto the barrels 201 and it preferably hooks around the loop. An Anson rod is used to detach the fore-end.

As will become more apparent, various embodiments relate to the provision of an inter-rib for a S/S or 0/U shotgun which is glued rather than soldered between the two barrels of a double barreled shotgun. Furthermore, according to various embodiments of the present invention an interlocking mechanism is provided for mechanically securing a top rib to a barrel during manufacture. In the case of an 0/U shotgun the top rib may be glued rather than soldered to the upper portion of the upper barrel in order to assist a user with targeting. A particularly beneficial aspect of various embodiments of the present invention is that gluing rather than soldering the two barrels together is a much simpler operation to perform and avoids hours of highly skilled labour which is involved conventionally in soldering two shotgun barrels together.

Furthermore, the application of the glue can be performed at relatively low temperatures whereas the conventional approach of soldering the two barrels together results in a significant amount of thermal energy being imparted to the barrels during manufacturing and assembly of the shotgun. According to various embodiments the glue may be cured at a relatively low temperature of approximately 140°C. It will be appreciated that such a temperature is significantly lower than the temperature at which conventional solder is applied to the barrels according to a conventional method.

It will be appreciated that the repeated application of heat to both shotgun barrels during a conventional soldering process is generally undesirable as it can cause damage to the barrels and the barrels may also become slightly misaligned. It will also be appreciated that any misalignment of the barrels during assembly is highly undesirable and is very labour intensive to repair. It will further immediately be appreciated, therefore, that the approach of gluing an inter-rib between two barrels of a shotgun enables both barrels to be perfectly aligned during assembly and advantageously significant thermal energy is not applied to the barrels during this stage of assembly.

Another significant advantage of various embodiments is that an inter-rib and/or optionally a top rib on an 0/U shotgun can be made from a lightweight material such as aluminum or carbon fibre. It will be appreciated that potentially reducing the weight of a shotgun has significant benefits. In some embodiments the benefit of potential weight reduction may be passed on fully to the user. In other embodiments, the benefit of potentially reducing the weight of the shotgun by avoiding using metal ribs may be fully or partially translated into making the barrels slightly thicker meaning that the barrels are -18 -more robust than a conventional shotgun.

The method of the present invention as described in more detail below also has a number of environmental benefits. The method of assembling a firearm according to the present invention is particularly advantageous from an environmental perspective in that: (i) a firearm when assembled according to the present invention is particularly suited for firing steel rather than lead shot; (ii) the method of assembling a firearm according to the present invention avoids any need to solder two ribs to two barrels of a double barreled shotgun thereby avoiding the use of environmentally harmful tin solder; and (iii) the method of assembling a firearm according to the present invention enables an assembled firearm to be blackened or otherwise provided with a final colouring without needing to use conventional chemicals to blacken or otherwise colour an assembled firearm.

According to various embodiments a firearm when assembled according to the present invention may be proofed to accept standard steel shot and also high performance steel shot. It will be apparent, therefore, that the method of assembling a firearm according to the present invention is particularly environmentally friendly.

Fig. 3 shows a barrel assembly of an 0/U shotgun according to various embodiments. The barrel assembly comprises a first (top) barrel 301, a second (bottom) barrel 302, an inter-rib 304 arranged between the two barrels 301,302 and a top rib 305 arranged upon the upper surface of the first (top) barrel 301. The two barrels 301,302 are mounted, in use, to a monoblock 306. According to various embodiments a S/S shotgun is also contemplated (not shown) wherein the barrels 301,302 are both arranged horizontally next to each other rather than being stacked vertically one above the other as is the case with an 0/U shotgun as shown in Fig. 3. The profiles of the two barrels 301,302 of a S/S shotgun and the profile of the inter-rib 304 of a S/S shotgun may either be the same or different to that of an 0/U shotgun. It will be appreciated that the two barrels 301,302 in a S/S shotgun arrangement are such that there is no upper barrel and hence the top rib 305 as shown in Fig. 3 may be omitted. Other embodiments are contemplated wherein with a S/S arrangement one or both barrels of the shotgun may optionally have a top rib 305.

In addition, or alternatively, the profile of the inter-rib 305 may be varied so that the inter-rib 305 extends or projects in one (e.g. vertically upwards) direction so that the top of the inter-rib 305 extends vertically upwards beyond the plane of the two side-by-side barrels 301,302. Accordingly, the upper portion of the inter-rib 305 may be used as a sight. The first 301 and second 302 barrels may be bonded to the monoblock 306 by use of a liquid adhesive and/or by laser welding rather than by traditional soldering methods.

According to various embodiments a laser may be used to laser weld the barrels 301,302 into the monoblock 306 around a seam. The inter-rib 304 and top rib 305 are preferably -19 -bonded to the first 301 and/or second 302 barrels by use of a liquid adhesive. As described in more detail below, the top rib 305 is preferably secured to the first (upper) barrel 301 using a dovetail interlocking mechanism. Methods for bonding, and materials used for the monoblock 306, first 301 and second 302 barrels, inter-rib 304 and top rib 305 are described in more detail below.

It will be appreciated that using a liquid adhesive to bond an inter-rib 304 between two barrels 301,302 of a shotgun, rifle or other firearm represents a significant departure from conventional manufacturing techniques and results in significant benefits in terms of a significant reduction in the need for highly skilled labour (to solder the two barrels 301,302 together), a stronger double barrel assembly as well as significant environment benefits by avoiding the use of fin solder. The shotgun barrel assembly is also stronger and more robust than conventional barrel assemblies enabling the shotgun to fire high performance steel shot rather than potentially environmentally harmful lead shot.

Furthermore, conventional blacking or colouring techniques involve the use of chemicals which will adhere to fin solder and steel ribs. However, according to various embodiments of the present invention no tin solder is used and likewise the inter-rib 304 and optional top rib 305 may be fabricated from other lightweight materials such as aluminium or a composite material. Accordingly, the shotgun barrels and related assembly may be blackened or coloured by different techniques using less harmful and/or less toxic chemicals or other processes.

Fig. 4 shows in further detail an inter-rib 304 according to an. The inter-rib 304 preferably comprises a metallic alloy. The metallic alloy may comprise an aluminium alloy, a titanium alloy or a magnesium alloy or any other suitable material. Alternatively, the metallic alloy may comprise a steel alloy. Alternative embodiments are also contemplated wherein the inter-rib 304 comprises a composite material. For example, the composite material may comprise carbon fibre, KEVLAR (RTM), graphite or glass fibre composite.

It is also contemplated that a discrete series of short length inter-ribs 304 may be provided with air gaps being provided between at least some of the inter-ribs 304. According to this embodiment the weight distribution along the length of the double barrel assembly may be varied. Embodiments are also contemplated wherein the series of inter-ribs 304 comprise two, three, four or more than four different materials.

For example, according to an embodiment some of the inter-ribs 304 may comprise a metallic alloy whilst other inter-ribs 304 may comprise a composite material. In a similar manner, one or more top-ribs 305 may be provided to either a 0/U or S/S shotgun and it is contemplated that a discrete series of short length top ribs 305 may be provided with air gaps being provided between at least some of the top ribs 305.

According to this embodiment the weight distribution along the length of the double barrel -20 -assembly may be varied. Embodiments are also contemplated wherein the series of top ribs 305 comprise two, three, four or more than four different materials. The inter-rib(s) 304 may be secured between the one or more barrels 301,302 by an interlocking mechanism and also by a liquid adhesive. The top rib(s) 305 may be secured to one or more barrels 301,302 by a liquid adhesive.

Various different embodiments are contemplated including the following: (i) an embodiment wherein both the inter-rib(s) 304 and top rib(s) 305 are secured to the barrels 301,302 by using a liquid adhesive; and (ii) an embodiment wherein the inter-rib(s) 304 are secured to the barrels 301,302 by using conventional techniques i.e. by use of tin solder and wherein the top rib(s) 305 is secured to the barrels 301,302 using an interlocking mechanism in combination with a liquid adhesive. In all embodiments, the firearm may comprise a shotgun, a rifle or a different class of firearm.

The firearm may comprise a single barrel in which case any inter-rib(s) 304 may be omitted but wherein one or more top ribs 305 are preferably glued to an upper surface of the single barrel using a liquid adhesive. According to a particularly preferred embodiment the liquid adhesive may comprise LOCTITE (RTM) 9514 which has been tested against other liquid adhesives and has been found to possess particularly favourable bonding characteristics. However, embodiments are not limited to the use of LOCTITE (RTM) 9514 to bond either two barrels 301,302 together via an inter-rib(s) 304 and/or to bond one or more top ribs 305 to one or both barrels 301,302. Other embodiments are contemplated wherein other adhesives including various acrylic adhesives may be utilised. LOCTITE (RTM) 9514 may be used according to various embodiments with both single barreled and double barreled firearms.

A plurality or series of inter-ribs 304 may be provided between two barrels 301,302 of the firearm. The plurality or series of inter-ribs 304 may be spaced apart in a longitudinal direction so that an arrangement of spacers is effectively provided between the two barrels 301,302 of the firearm. It will be understood that such an arrangement is particularly effective in providing a method of air venting or air cooling of the barrels 301,302 when the firearm is in use. This is particularly beneficial if the firearm is used for clay pigeon shooting where a large number of shots may be fired in a short period of time with the result that the barrels 301,302 will get particularly hot. Advantageously, it has also been found that using LOCTITE (RTM) 9514 and other similar adhesives has beneficial thermal properties compared to the use of tin solder.

In particular, according various embodiments a barrel assembly which is preferably assembled utilising a liquid adhesive is more robust and stronger than a conventional shotgun wherein the tin solder can begin to deteriorate over a period of time when subjected to high temperatures for a sustained period of time. Accordingly, a firearm -21 -according to the present invention requires less servicing and repair than a conventional shotgun. In another embodiment, for a firearm with a S/S configuration, a single inter-rib 304 may be provided which preferably also acts as a top rib thereby making the need for a discrete or separate top rib redundant. The top rib section 305 may be adapted to form a sight so as to assist a user or shooter when aiming the firearm at a target.

Fig. 5 shows a top rib 305 according to an embodiment. In an 0/U arrangement, the firearm may comprise a separate top rib 305 which is provided along at least a portion of the length of the upper or top barrel 301 to assist with aiming. Alternatively, in a S/S arrangement one of the barrels or both barrels may comprise a top rib 305. The top rib 305 preferably comprises a metallic alloy. The metallic alloy may comprise an aluminium alloy, a titanium alloy or a magnesium alloy or any other suitable material. Alternatively, the metallic alloy may comprise a steel alloy. Alternative embodiments are contemplated wherein the top rib 305 comprises a composite material. For example, the composite material may comprise carbon fibre, KEVLAR (RTM), graphite or glass fibre composite.

In various embodiments the top rib 305 may be secured to the one or more barrels 301,302 by a liquid adhesive. According to an embodiment the liquid adhesive may comprise LOCTITE (RTM) 9514. However, other embodiments are contemplated wherein other adhesives including an acrylic adhesive may be utilised. The top rib 305 may be manufactured so that it can either be vented or non-vented to aid in heat dissipation when the firearm is being used.

Fig. 6 shows a portion of the action including a top strap for illustrative purposes only. Specific details relating to the action fall outside the scope of the present invention and hence are omitted from further discussion.

Fig. 7 shows a monoblock 306, a first barrel 301 and a second barrel 302 and laser weld positions 752 of the first barrel 301 and second barrel 302 when placed in the monoblock 306 according to an embodiment. The first barrel 301 and the second barrel 302 may comprise specialist steel such as 709M40T or CARRSP20 or any other suitable metallic alloy. The first barrel 301 and second barrel 302 may have a suitable liquid adhesive applied to the outer breech ends. According to an embodiment LOCTITE (RTM) 648 may be applied before being placed and secured into position in the monoblock 306.

Any excess adhesive is preferably removed at this stage optionally by use of a solvent.

The bonding of the first 301 and second barrels 302 is preferably carried out at lower temperatures compared to conventional solder techniques. This further advantageously avoids oxidation of the barrel surface. The lower temperatures also allow for the first 301 and second 302 barrels to be held in place by use of jigs and other features (not shown) thereby improving accuracy of the assembly process. It will be understood that the accurate assembly and alignment of the two barrels 301,302 is a highly skilled manual -22 -task.

Although the assembly and alignment of the two barrels 301,302 remains a significantly skilled task it will be understood that the process of assembling the barrels 301,302 together can be made significantly quicker, easier and cheaper. After a suitable amount of time, to allow the liquid adhesive to successfully bond the first 301 and second barrels 302 into the monoblock 306, the first 301 and second barrels 302 are preferably securely welded into place in the monoblock 306 preferably by laser welding or electron beam welding.

Securing the first 301 and second 302 barrels to the monoblock 306 in this way, by first applying a liquid adhesive to the outer breech end of the first 301 and second 302 barrels, bonding the first 301 and second 302 barrels to the monoblock 306 using a liquid adhesive, followed by laser welding (or electron beam welding) the first 301 and second 302 barrels to the monoblock 306 advantageously simplifies the process of obtaining a fully sealed joint between the first 301 and second 302 barrels and the monoblock 306, without the presence of voids.

Thus in various embodiments, the lower temperatures used when bonding the first 301 and second 302 barrels to the monoblock 306 with liquid adhesive combined with the removal of excess liquid adhesive prior to laser welding (or electron beam welding)also advantageously results in less distortion of the assembly with small, clean welds 752 with minimal heat affected zones to the first 301 and second 302 barrels steel. Furthermore, as the liquid adhesive is non corrosive, once cured it acts as a protective coating. This mitigates the issues commonly found with traditional methods of construction.

Fig. 8 shows an inter-rib 880 according to a further embodiment which can be used in either a S/S or 0/U configuration of a firearm. The inter-rib 880 may have material removed throughout the cross-section depending on specific user requirements resulting in a number of slots or holes 890 being arranged throughout. The removal of material may be achieved my milling, drilling or other suitable methods. According to various embodiments the inter-rib 880 may comprise a skeletonised inter-rib 880. It is also contemplated that a plurality of skeletonised inter-ribs 880 may be utilised with air gaps between them. Various combinations of skeletonised inter-ribs 880 and non-skeletonised inter-ribs 304 as described above may be provided. Similarly, one or more skeletonised top ribs may be provided.

Embodiments are contemplated wherein a firearm is provided comprising one or more inter-ribs 304,880 and/or one or more top ribs 305, wherein either the one or more inter-ribs 304,880 and/or the one or more top ribs 305 comprise either solid non-apertured rib(s) and/or skeletonised or otherwise apertured rib(s). The inter-rib 880 preferably is -23 -comprised of a metallic alloy or composite material. The metallic alloy preferably comprises an aluminium alloy, a titanium alloy or a magnesium alloy or any other suitable material. Less preferably the metallic alloy may comprise a steel alloy. The composite preferably comprises of carbon fibre, KEVLAR (RTM), graphite or glass fibre composite.

Forming the inter-rib 880 in this way provides the distinct advantage of customising weight distribution as may be required or requested by the user. For example, a particular arrangement of slots or holes 890 on the inter-rib 880 can change the position of the center of gravity of the firearm, advantageously resulting in customisability of shooting characteristics and gun handling.

For example, a firearm manufactured with a large number of holes or slots 890 throughout the inter-rib 880 will provide a firearm that is lightweight, resulting in high manoeuvrability which is useful for fast gun handling for game shooting. However, this can also result in high muzzle flip. Conversely, a firearm manufactured with a smaller number of holes or slots 890 on the inter-rib 880, will result in a heavier firearm. Maneuverability characteristics will be reduced, but muzzle flip will also be greatly reduced. Reduced muzzle flip is particularly suited to sports such as clay shooting wherein the reduced muzzle flip results in a steadier barrel and a faster second shot.

Fig. 9A shows corrosion of an 0/U top rib when constructed using traditional methods. Fig. 9B shows corrosion of a S/S top rib. As shown, a known problem with rib forms and fixings including both top ribs and inter-ribs is the failure of soldered joints over time. As can be seen in Figs. 9A and 9B the joint surfaces are often narrow lines with small contact areas. In these known methods, repair of the soldered joints is common.

Often after repair the tubes can be deflected and misaligned due to the difficulty of securing them during the heating and soldering process.

An additional failure mode from this known method of construction is that of corrosion which can occur in the void between the barrel tubes. This corrosion can be exacerbated with the heating and cooling cycles experienced by the firearm when in use and in particular during wet weather conditions as moisture is drawn into the void between the barrels. As this cycle repeats overtime the corrosion will creep under the solder joints and detach them providing a failure in the joint and consequently a failure of the structural integrity of the barrel assembly.

If the corrosion cycle is not addressed then this can lead to a brown rust like slurry appearing which can propagate further into the fore and action itself (not pictured) causing significant further corrosion damage of the firearm. If the solder flux is a corrosive type, this will further exacerbate the corrosion process. Corrosive flux is normally used for conventional barrel assembly. If a non-corrosive resin flux were to be used then it is more -24 -difficult to achieve a wetting of the surfaces to be jointed of the barrel assembly, a process which is conducted at higher temperatures than liquid adhesive bonding.

In the conventional method of assembly, solder is applied to the joint which results in excess solder leaching out onto the visual surfaces, which then needs to be mechanically scraped off, followed by polishing. There is a further risk that the barrel thickness may be reduced to an unsafe thickness if too much material is removed during this process. The excess solder leaching and laborious requirement of mechanical scraping and polishing provides a further issue, as the particular type of solder used in the industry contains some quantity of lead, providing a significant health hazard to the assembler. Moreover, the excess solder from the joints often extends onto the visual surfaces of the barrel assembly. If this is not fully cleaned before the barrel assembly undergoes a common "blacking" process, aesthetic qualities of the firearm are negatively impacted.

Figs. 10A-C shows a method of laser welding barrel tubes 1001 into a monoblock 1002 according to an exemplary embodiment of the present invention. Traditional methods require soft soldering of the individual tubes 1001 into the monoblock 1002.

The joint surface 1003 is small and hence getting the complete joint surface 1003 of the barrel tube 1001 to bond to the monoblock 1002 is difficult to achieve. The visible shoulder joint 1003 at the front of the monoblock 1002 if not perfectly sealed will cause issues with "blacking" or colouring as the crevasse can release contaminates which affect the "blacking" or colouring process. Conversely, in an embodiment and as shown in Fig. 10A, liquid adhesive is first applied to the outer breech end of the barrel tubes 1001, followed by inserting and bonding the barrel tubes 1001 into the monoblock 1002. Any excess adhesive can be wiped away before the barrel tubes 1001 are laser welded to the monoblock 1002.

Fig. 103 shows the barrel tubes laser welded to the monoblock according to an embodiment. In a conventional method of assembly solder is applied to the joint, which results in excess solder leaching out onto the visual surfaces, which needs to be mechanically scraped off, followed by polishing. There is a further risk that the barrel thickness may be reduced to an unsafe thickness if too much material is removed during this process.

Conventionally, excess solder from the joints extends onto the visual surfaces of the barrel assembly. If this is not fully cleaned before the barrel assembly undergoes a common 'blacking' process, aesthetic qualities of the firearm are negatively impacted.

According to an embodiment, the excess adhesive applied to the barrel tubes 1001 after insertion into the monoblock 1002 can simply be wiped away using a solvent prior to laser -25 -welding resulting in small, clean welds 1003 with minimal heat affected zones to the barrel tubes 1001 steel. Therefore, the barrels 1001 can be smoothed over easily after this process, as illustrated in Fig. 10C. This in part is also made easier due to appropriate weld preparations on both the barrel tubes 1001 and monoblock 1002 prior to laser welding. It will be appreciated, therefore, that the present invention is particularly advantageous and represents a significant advance in the art of assembling, manufacturing or repairing a component of a firearm.

It will be appreciated that a top rib 305 of a shotgun may be subjected to physical knocks or slightly rough handling from a user or by those charged with transporting the shotgun at a day's shooting. For example, the top rib 305 may receive a knock in a lateral direction which is perpendicular to the longitudinal length of the barrels 301,302 and in particular the top rib 305 may receive a knock on the side of the top rib 305 towards the muzzle end. It will be understood that the top rib 305 preferably tapers in terms of cross-sectional profile or height towards the muzzle end. In particular, at the muzzle end of the assembly, the top rib 305 may thin towards the muzzle.

In order to further strengthen the top rib 305 to the upper barrel 301 an interlocking system has been developed. With reference to Fig. 11A according to an embodiment one or more small male dovetail sections 1100a,1100b may be precision laser welded onto an upper surface of the top or upper barrel 301 of a double barrel assembly. A specialist fixture may be used to accurately locate the dovetail piece(s) 1100a,1100b before the one or more pieces 1100a,1100b are welded into position onto the top barrel 301. The male dovetail piece(s) 1100a,1100b may be attached to upper barrel 301 in other ways. Due to the precision nature and controllability of the laser welding system and in particular control of the energy used to weld the one or more dovetail pieces 1100a,1100b onto the upper barrel 301, no distortion of the precision manufactured barrels 301,302 will result.

According to an embodiment one or more corresponding female dovetail forms 1101a,1101b may be precision machined into the top rib 305 along the centre line of the top rib 305. The top rib 305 with its female dovetail slot(s) 1101a,1101b and the male dovetail piece(s) 1100a,1100b precision welded onto the top barrel 301 may then be brought together as an interlocking assembly. According to an embodiment at the same time that the top rib 305 is interlocked to the upper barrel 301, the top rib 305 may also be glued to the upper barrel 301 in order to further secure the two components together.

Fig. 11B shows the top rib 305 secured to the upper barrel 301 after having been interlocked to the upper barrel 301 and also glued to the upper barrel 301. According to an embodiment an epoxy adhesive may be used to secure the top rib 305 to the upper barrel 301. According to an embodiment spacers or packing pieces may be placed at 90° to the top rib 305. The spacers or packing pieces may be approx. 30 mm long and may -26 -comprise a bundle of 30-50 individual filaments. The spacers or packing pieces may comprise a bundle of individual filaments such that the bundle has a total thickness of approx. 50-80 pm i.e. approximately the same thickness as a human hair.

The use of spacers or packing pieces enables there to be enough adhesive in contact between the top rib 305 and the upper barrel 301 for an optimal bond to be formed. In particular, the use of spacers or packing pieces ensures that the adhesive is not squeezed out completely and that a 50-80 pm gap or thickness of adhesive is left between the top rib 305 and the upper barrel 301. According to various embodiments filament bundles may be repeatedly laid along the length of the upper barrel 301 and the upper barrel 301 and the top rib 305 may be clamped together. It will be apparent, therefore, that bundles of spacers or packing pieces may stick out but these may be trimmed off with a sharp blade once the adhesive has cured slightly or completely.

Fig. 12 shows in greater detail an embodiment wherein a male dovetail projection 1100a is provided towards the muzzle end of the upper barrel 301 and a corresponding female dovetail recess 1101a is provided in a lower surface of the top rib 305. The top rib 305 may then be slid on to the top barrel 301 such that a wider section of the female dovetail recess 1101a initially engages with the male projection 1100a. As the top rib 305 is progressively slid along the length of the upper barrel 301 in a direction away from the muzzle end of the barrel assembly, the male dovetail projection 1100a may then become secured within a reduced width portion of the female dovetail recess 1101a.

With reference to Fig. 13, after the interlocking has taken place, at the monoblock end 306 of the assembly, the top rib 305 has a section which may nestle under a defined feature on the monoblock 306. This again provides a mechanical interlocking of the tail of the top rib 305 into the monoblock 306. Once the assembly has cured within the bonding fixture, and the assembly has had the excess adhesive removed, the assembly is then ready to progress onto the next process step. It will be understood that the top rib 305 is securely bonded and mechanically interlocked to the upper barrel 301 so that the assembly can be handled robustly during the subsequent assembly stages.

Although the present invention has been described in connection with specific exemplary embodiments, it should be understood that various changes, substitutions, and alterations apparent to those skilled in the art can be made to the disclosed embodiments without departing from the scope of the invention as set forth in the appended claims. -27 -

Claims (28)

1. Claims 1. A method of assembling, manufacturing or repairing a component of a firearm comprising: providing a first barrel having one or more first interlocking features; providing a top rib having one or more second interlocking features; and securing the top rib to the first barrel by engaging the one or more first interlocking features with the one or more second interlocking features.
2. 2. A method as claimed in claim 1, wherein the step of engaging the one or more first interlocking features with the one or more second interlocking features comprises moving or sliding the one or more first interlocking features relative to the one or more second interlocking features.
3. 3. A method as claimed in claim 1 or 2, wherein the one or more first interlocking features comprise one or more projections and the one or more second interlocking features comprise one or more recesses.
4. 4. A method as claimed in claim 1 or 2, wherein the one or more first interlocking features comprise one or more recesses and the one or more second interlocking features comprise one or more projections.
5. 5. A method as claimed in claim 3 or 4, wherein the one or more recesses have a female dovetail or trapezoidal cross-sectional profile.
6. 6. A method as claimed in claim 3, 4 or 5, wherein the one or more projections have a male dovetail or trapezoidal cross-sectional profile.
7. 7. A method as claimed in any preceding claim, further comprising additionally securing the top rib to the first barrel using a liquid adhesive.
8. 8. A method as claimed in claim 7, wherein the liquid adhesive is selected from the group comprising: (i) anaerobic; (ii) epoxy 1 and 2 pack; (ffi) acrylic 1 and 2 pack; and (iv) polyurethane 1 and 2 pack.
9. 9. A method as claimed in any preceding claim, wherein the top rib comprises either a non-vented top rib or a vented top rib.
10. 10. A method as claimed in any preceding claim, wherein the first barrel comprises metal or a metallic alloy. -28 -
11. 11. A method as claimed in claim 10, wherein the metal or metallic alloy comprises steel such as 709M40T, CARRS-P20, EN19T or EN24T.
12. 12. A method as claimed in any preceding claim, further comprising securing the first barrel to a second barrel to form a double barrel assembly.
13. 13. A method as claimed in claim 12, further comprising securing one or more inter-ribs or spacing elements between the first barrel and the second barrel.
14. 14. A method as claimed in claim 13, wherein the one or more inter-ribs or spacing elements are secured along at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90% of the longitudinal length of either the first barrel and/or the second barrel.
15. 15. A method as claimed in claim 13 or 14, wherein the one or more inter-ribs or spacing elements comprise a metallic alloy or a composite.
16. 16. A method as claimed in claim 15, wherein the metallic alloy is selected from the group consisting of: (i) an aluminium alloy; (ii) a titanium alloy; and (iii) a magnesium alloy.
17. 17. A method as claimed in claim 15 or 16, wherein the composite comprises a carbon fibre or glass fibre composite.
18. 18. A method as claimed in any of claims 13-17, wherein one or more sacrificial sections are used to hold the one or more inter-ribs or spacing elements during manufacture and wherein optionally the one or more sacrificial sections are removed or machined off post-manufacture.
19. 19. A method as claimed in any preceding claim, wherein the firearm further comprises a monoblock and wherein the method further comprises the step of securing a first end of the first barrel to the monoblock using laser welding, electron beam welding or gluing and/or securing a first end of a second barrel to the monoblock using laser welding, electron beam welding or gluing.
20. 20. A method as claimed in claim 19, wherein the step of securing the first end of the first barrel to the monoblock using laser welding, electron beam welding or gluing and/or securing a first end of the second barrel to the monoblock using laser welding, electron beam welding or gluing is performed prior to and/or subsequent to the step of securing one or more inter-ribs or spacing elements between at least the first barrel and the second barrel using a liquid adhesive.
21. 21. A method as claimed in claim 19 or 20, wherein the step of securing the first end -29 -of the first barrel to the monoblock using laser welding, electron beam welding or gluing and/or securing a first end of the second barrel to the monoblock using laser welding, electron beam welding or gluing is performed prior to and/or subsequent to the step of securing the top rib to the first barrel.
22. 22. A method as claimed in claim 19, 20 or 21, wherein the first barrel and the second barrel are secured in the monoblock so as to be angularly converging at an angle < 1° relative to each other.
23. 23. A component of a firearm comprising: a first barrel having one or more first interlocking features; a top rib having one or more second interlocking features; wherein the top rib is secure to the first barrel by engagement of the one or more first interlocking features with the one or more second interlocking features.
24. 24. A firearm comprising: a component as claimed in claim 23.
25. 25. A firearm as claimed in claim 24, wherein the firearm comprises a double barreled shotgun, wherein the first barrel and the second barrel of the shotgun are arranged in an over-under (0/U) arrangement or a side-by-side (S/S) arrangement.
26. 26. A method of assembling, manufacturing or repairing a component of a firearm comprising the steps of: (a) securing one or more inter-ribs or spacing elements between a first barrel and a second barrel using a liquid adhesive; (b) attaching one or more first interlocking features to the first barrel and providing a top rib having one or more second interlocking features; (c) securing the top rib to the first barrel by engaging the one or more first interlocking features with the one or more second interlocking features; and (d) laser welding, electron beam welding or gluing the first and second barrels to a monoblock.
27. 27. A method as claimed in claim 26, further comprising performing step (a) before or after step (b).
28. 28. A method as claimed in claim 26 or 27, further comprising performing step (a) before or after step (c).