US3157121A - Shotshell - Google Patents

Description

N09- 17, 1964 B. K. DAuBENsPEcK ETAL 3,157,121

SHOT SHELL Filed April 5, 1963 a 4 2 y wi United States Patent Oli 3,157,121 Patented Nov. 17, 1964 ice 3,157,121 SHOTSHELL Benjamin K. Daubenspeck, Stratford, Theodore A. ison, Trumbull, Edward A. Rickey, Stratford, and Justin H. Whipple, Milford, Conn., assignors to Remington Arms Company, Inc., Bridgeport, Conn., a corporation of Delaware Filed Apr. 5, 1963, Ser. No. 276,983 12 Claims. (Cl. IGZ-42) This invention relates in general to shot cartridges and more specifically to providing improved shotshell components which improve the reloadability and functioning of the shotshells.

Current basewad designs are limiting the reloadability and functioning of todays shotshells. The limiting factors are breakdown of the basewad itself and excessive head expansion during tiring due to the basewad failing to seal properly and failing to properly absorb the pres* sures generated in the shell when tired. The acceptable life of basewad designs currently being used is considered to be 3,0r 4 tirings.

The novel basewad design of the present invention will overcome the above-mentioned deficiencies. With the design of the present invention, the acceptable life of the basewad is considered to be to 12 lirings.

This invention consists of a basewad encased in a plastic (polyethylene) sleeve which is contoured at one end to provide a positive, gas sealing overlay. The basewad is suiiciently hard and pressure absorbing so that a minimum of tiring pressure is transmitted tov the head. Head expansion is therefore reduced, resulting in easier extraction and minimizing head resizing during reloading of the tired shell. In addition, this overlay-hard wad construction improves gas sealing over conventional basewads. The fact that the wad is completely enveloped in plastic means that no wad debris will be encountered in tiring these shells. The wrap-around plastic skirt, tucked under the basewad, insures positive locking ofthe overlay. This means that the overlay will not be blown out of the shell on the second or third firing as can happen with paper overlays presently on the market. Since the flash hole in the basewad is also lined with plastic in this combination, no fibrous material will be exposed to the blast of the exploding primer. The resultant smooth even surface of the ash hole should contribute to more stable ignition.

Another important and substantial advantage of the present invention is that with the complete plastic wraparound design of the' liller basewad, the transfer of moisa ture from the basewad to the powder or from the powder to the basewad is essentially eliminated. In a plastic shell, this is an important feature,'inasmuch as ballistics can be maintained for the shell over extended periods of time.

The loss of powder moisture increases firing pressures and the absorption of moisture by the powder will reduce tiring pressures which naturally adversely affects velocity. The transfer of moisture, of course, depends on the relative dierence in moisture content between the propellant powder and the basewad.

v This moisture transferring limitation is extremely important with single base powders, i.e., those made by dissolving nitrocellulose in an ether-alcohol solvent, extruding and .then drying out. On the other hand, the transfer of moisture does not alfect the sensitivity of the double base powder, i.e., those made by gelatinizing nitrocellulose with nitroglycerin, to the same degree. When the powder absorbs moisture, there is a resulting loss of pressure and velocity which affects the performance of the shotshell. By segregating the powder and basewad with a plastic overlay, this transfer of moisture is essentially eliminated with the result being a more uniform and reliable product.

It is known that the combination of a plastic overlay and a basewad is old in the art. However, in the past, the impact strength of the basewad was limited because it was necessary that the basewad have a certain amount of resiliency in order for the basewad to expand sutiiciently to act as a gas sealing means to protect the cartridge head. By providing a resilient plastic overlay which substantially encloses the basewad, it is possible to make the basewad substantially harder and more pressure absorbing and let the gas sealing function be performed almost entirely by the plastic overlay. Thus, with this combination, basewads can be made with materials which would not have been acceptable iu the past.

The object of this invention is to provide a shotshell wherein the gas leakage around the basewad is substantially decreased and head expansion reduced.

It is another object of this invention to provide a plastic overlay which substantially encloses the basewad and prevents explosive gases from coming into contact with the basewad.

Another object of this invention is to provide an overlay which is effectively locked to the shotshell head.

Another object of this invention is to provide a plastic basewad overlay which permits the use of basewad having a hardness which were previously not acceptable.

Further objects will appear in the accompanying specication and claims in which:

FIGURE 1 shows a longitudinal sectional view of shot cartridge embodying the present invention;

FIGURE 2 shows a longitudinal sectional view of a shotshell casing with the basewad and plastic overlay positioned therein before a low base head is attached thereto;

FIGURE 3 shows a sectional view of the metal head prior to attachment to the shotshell shown in FIGURE 2; and

FIGURE 4 shows a cross-sectional View of the shell taken on Line 4-*4 of FIGURE 2. y

Referring to the drawings, FIGURE 1 shows an elongated tubular shotshell bodyv 0r casing 10 which can be made of plastic, paper, metal or any other suitable material. A metal head portion 12 is attached to the lower end of the casing as explained below.

Positioned within the lower end of the shell body 10 is a pre-assembled basewad-plastic overlay combination 14 consisting of a plastic overlay 16 land a basewad 18. The shotshell also includes the usual primer 20, a propellant charge 22, anover-powder wad 24, ller wads 26 and the shot pellets 28. The upper end of the shotshell body is closed olf by any well-known closure means (not shown).

Inasmuch as the present invention is believed to be in the basewad-overlay combination and their relationship to the shotshell, these elements will be explained in greater detail.

The plastic overlay 16 includes an elongated tubular wall portion .3d having approximately the same diameter as the body 10 so that when the overlay Ais positioned within the body, a tight fit is effected between the wall .portion 3@ and the lower end of the shell body.

functions as a gas seal to prevent explosive gas fromv escaping down behind the basewad. v The transverse wall portion 32 also has a central opening 36 therein which is in alignment with an axial andelongated basewad hole 38 and a hole 40 in the metal head 12. These three holes 36, 38 and 40 constitute the ash hole means in which the primer is located and through which the ame from the detonated primer escapes to ignite the propellant charge 22. As can be seen in FIGURE 2, an elongated, tubular wall portion 42, concentric with the tubular wall portion 30, is integral with and projects downwardly from the periphery of the central opening 36 through the hole 38 in the basewad to provide a smooth lining for the ash hole means.

It can be seen from FIGURE 2 that the lower end 44 of the tubular wall 30 and the lower end 46 of the inner wall portion 42 extend downwardly past the lower end face 48 of the basewad when the basewad is inserted in the plastic overlay soy that the basewad is enclosed by the plastic overlay except for the lower end face 48 of the basewad.

` The shell assembly procedure begins with the full insertion of the basewad into the overlay. The overlay-wad is then positioned in the shell body and the lower ends crimped inwardly to permit entrance into the head 12. (See FIGURES` 2 and 3.) The overlay-wad and body combination are then inserted into the half-headed cap shown in FIGURE 3. Prongs 50 in the head are coned inwardly to insure easy insertion into the tubular extension 46 of portion 42. When the head is finally attached to the shotshell body (after the final heading operation), the rim of the cap is closed on itself and on any outwardly flared part of the shell body, as shown in FIG- UREV l. Moreover, the overlay skirt portions 44 and 46 are tucked under thev basewad both in the rim area and in the primer area. The prongs 50 on the head are opened up by the cavity punch during the heading operation and firmly grip the overlay tube against the basewad. From the above, it can be seen that with the tucking in of the overlay lower skirt portions 44 and 46, the basewad is substantially entirely enclosed by the plastic overlay.

As mentioned previously, this use of the plastic overlay gas sealing means permits the use of materials in basewad construction which were not used previously because they were ineffective for this purpose. A suitable wad for this combination has been made by several different methods. All of these wads have suilicient resistance to deformation under pressure to produce the desired, results.

In one method of making the wad, hard maple wood fibers.. are coated withA sodium meta-silicate and sodium aluminate solutions. The proportions of silicate to aluminate are about fourV to one, and the total additive is about percent of the weight of the liber as received. The components are blended in a mixer with the addition of theA aluminate dissolved in the water equivalent of about 3 percent of the fiber weight. When thoroughlyY mixed, the silicate is added in the form of an approximately 40 Baume solution meta-silicate solution with sufficient water to be equivalent to about 4 percent of the fiber weight. After mixing in the silicate, the composition is dried to about 6 percent moisture content based on the original fiber weight. The dried composition is then used for compression molding of the wad in a conventional tableting typemachine.

Another method of making a suitable wad uses normal Portlandcement as a binder with maple and other fillers, such as plastic flour (and/or asbestos fibers) plus wax.v A typical mixture found to be satisfactory is:

Percent Maple liber 51.3 Plastic our (phenolic plastic waste material) 47.5 Asbestos 1.0

Wax (synthetic hard waxes or microcrystalline petroleum waxes) Percentages are dry weight.

About 4 to `12 percent of Portland cement, based on the total weight of the fibers, is added to the composition.

The method-of preparing the composition is to mix the ller ingredients intimately in a suitable mixer. The

cement is added as a dispersion in a water equivalent of about 5 to 8 percent of the total filler weight. After the cement addition, the mixing is continued until the cement is completely blended with the other materials. This mixture requires no drying but the wads (made by compression molding) shonld be aged for at least 24 hours at room conditions for best results.

A suitable wad can also be made from fibers coated with gypsum (CaSO4-I-I2O) by simple mixing. A solution of polynierized resin dispersion containing the necessary water of hydration is added to the mix. A typical mixture is:

Percent Hardwood liberor 461/2 hardwood+461/r% plastic flour 93 Plaster of Paris 7 By fiber wt. of 5% polyvinyl alcohol solution 9 The use of more concentrated polyvinyl alcohol solutions would improve the impact strength of the wad.

The prepared molding compositions for the various kinds of wads can be agedV indefinitely at normal conditions before use.

Instead of using polyvinyl alcohol solution, it has been found that other polymerized resin dispersions can also be used in the last mentioned method. Thus, such resin dispersions as polyvinyl chloride, polyvinyl acetate, and styrene butadiene can also be used in place of polyvinyl alcohol.

From the foregoing description, it is obvious that the invention is not intended to be limited to the details of construction shown in the drawings or explained in the specication but rather as dened in the claims.

What is claimed is:

l. A shot cartridge having a shell, said shell comprising a tubular casing having one end thereof closed ot by a head, a propellant charge positioned within said casing and spaced from said head, a basewad positioned within the casing between the propellant charge and the head, ash hole means in said basewad adapted to receive av priming device, and an overlay means substantially cornpletely enclosing said basewad thus providing a tight seal*y between the basewad and the head, the basewad and the tubular casing, and the basewad and the propellant charge.

2. A shot cartridge as recited in claim l wherein said overlay means comprises an integral, molded, resilient member having an outer tubular wall casing which fits between the basewad and the shell casing, a transverse wall portion intermediate the ends of the outer wall casing and underlying the propellant charge, an opening in the* transverse wall portion which is in alignment with and provides an extension of said liash hole means, and a -tubular liner integral with and projecting downwardly froml the periphery of said transverse wall opening into said' flash hole means to define a continuous lining for the flash hole means.

3. A shot cartridge having a shell with a head at one end thereof, a propellant charge spaced from said head, a basewad having a central opening therein, said basewad being positioned between-said propellant charge and said head, and resilient means substantially completely enveloping said basewad to provide a positive gas-sealing overlay.

4. A shot cartridge as recited in claim 3 wherein said resilient means comprises a transverse wall portionpositioned between the propellant charge and the basewad, skirt means extending upwardly from said transverse wall portion to act as a gas-sealing means, and tubular side wall means projecting downwardly from the transverse yWall'between the basewad and the lower portion of the shell, the lower end portion of said side wall means being turned inwardly and held positively in place between the bottom face of the basewad and the head.

5. A shot cartridge as recited in claim 4 in which a tubular liner means projects downwardly from said transverse wall portion through aligned flash holes in said baseenamel Wad and said head and having the lower ends of the tubul-ar liner means extend inwardly between `the basewad and head, thus forming a continuous and secured lining for said ash holes.

6. A shot cartridge having a shell With a head at one end thereof, a propellant charge spaced from said head and positioned within said shell, a basewad having a central opening therein positioned between said propellant charge and said head, said basewad being suiliciently hard and pressure absorbing so that a minimum of ring pressure is transmitted to the head, and a plastic overlay means which substantially completely envelopes said base- Wad to provide a positive gas seal.

7. In a shotshell having a head at one end and a propellant charge spaced therefrom, the combination of a basewad and resilient overlay designed to prevent excessive head expansion during firing due to the basewad failing to seal properly and failing t-o properly absorb the pressures generated in the shell when red, said combination comprising said basewad which is suiciently hard and pressure absorbing so that a minimum of tiring pressure is transmitted to the head, and said resilient overlay substantially entirely enclosing said basewad to prevent eX- plosive gas pressure from coming in Contact with said basewad and said casing head thus preventing excessive head expansion.

8. In a shotshell as recited in claim 7 wherein said base- Wad is made of hard maple wood bers coated with sodium meta-silicate and sodium aluminate.

9. In a shotshell as recited in claim 7 wherein said base- Wad is made from bers coated with gypsum and mixed with a polymerized resin dispersion.

10. In a shotshell as recited in claim 7 wherein the essentially major ingredient making up the basewad is i fibers with a relatively minor portion of binder, said binder comprising about 4-12% of Portland cement based on the total weight of the filler and minor amounts of wax.

11. In a shotshell as recited in claim 7 wherein said basewad is made of ller material comprising primarily substantially equal portions of maple bers and plastic ilour and a relatively minor portion of asbestos, and a binder material comprising about 4-12% of Portland cement based on the total weight of the filler andminor amounts of wax depending on the ultimate basewad physical characteristics desired.

12. In a `shotshell as recited in claim 7 wherein said basewad is made essentially of approximately equal portions of hardwood ibers and plastic ilour with varying minor amounts of gypsum and polyvinyl alcohol, depending on the ultimate characteristics desired.

References Cited in the lile of this patent UNITED STATES PATENTS

Claims (1)

1. A SHOT CARTRIDGE HAVING A SHELL, SAID SHELL COMPRISING A TUBULAR CASING HAVING ONE END THEREOF CLOSED OFF BY A HEAD, A PROPELLANT CHARGE POSITIONED WITHIN SAID CASING AND SPACED FROM SAID HEAD, A BASEWAD POSITIONED WITHIN THE CASING BETWEEN THE PROPELLANT CHARGE AND THE HEAD, FLASH HOLE MEANS IN SAID BASEWAD ADAPTED TO RECEIVE A PRIMING DEVICE, AND AN OVERLAY MEANS SUBSTANTIALLY COMPLETELY ENCLOSING SAID BASEWAD THUS PROVIDING A TIGHT SEAL BETWEEN THE BASEWAD AND THE HEAD, THE BASEWAD AND THE TUBULAR CASING, AND THE BASEWAD AND THE PROPELLANT CHARGE.

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