AU667542B2

AU667542B2 - Improved rifle

Info

Publication number: AU667542B2
Application number: AU41504/93A
Authority: AU
Inventors: Arthur William Langsford
Original assignee: Langsford Myra Mavis
Current assignee: Langsford Myra Mavis
Priority date: 1992-07-07
Filing date: 1993-06-25
Publication date: 1996-03-28
Anticipated expiration: 2013-06-25
Also published as: AU4150493A

Description

PI

9 L c B a 667542

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Regulation 3.2 rti ri Pi t 4 1( Name of Applicant: ARTHUR WILLIAM LANGSFORD Actual Inventor: ARTHUR WILLIAM LANGSFORD Address for Service: R K MADDERN ASSOCIATES, 345 King William Street, Adelaide, South Australia, Australia Invention title: "IMPROVED RIFLE" Details of Associated Provisional Application No: PL 3355 dated 7th July 1992 The following statement is a full description of this invention, including the best method of performing it known to me.

This invention relates to a rifle, and in particular to the size relationship between the nominal size of the projectile and the bore of the rifle barrel.

For simplicity of explanation, in this description, a rifle primarily comprises a firing chamber which is connected to or adjacent a rifle barrel. The firing chamber has a loading mechanism which positions a cartridge and accompanying projectile within the chamber such that upon firing of the cartridge, the projectile is directed through the rifle barrel.

This invention relates 4 bath pan- w 1 l e h l o to barrels having a plurality of spiral rifling grooves along the rifle bore.

.qq9ol For many years, it has been known that rifling grooves within a barrel, which cause a projectile to spin, will follow a o: much flatter trajectory than the same missile that leaves a rifle barrel without the spinning. In this regard, a great deal of effort has been applied to improve rifles so as to obtain the flattest possible trajectory of the projectile.

It is also regarded as desirable that the projectile should maintain as much momentum or impact force as possible and obviously, attempts have been made to increase the power of the rifle by using larger propellant charges within a cartridge.

Therefore, it is an object of this invention to provide a rifle which produces a flat trajectory while at the same time maximising projectile momentum.

In its broadest form, the invention may comprise a rifle having a firing chamber to receive a cartridge and projectile of nominal size, said firing chamber coupled to a rifle barrel, the diameter of the bore of said rifle barrel being smaller than said nominal size of said projectile such that -laduring discharge said projectile is reduced in diameter upon travelling through said rifle bore.

Preferably, the bore of the rifle is smaller than the nominal size of the cartridge and projectile by at least The inventor has found that significant improvements in relation to projectile energy can be achieved with a rifle bore size which is smaller than the nominal size of the cartridge by between 8 and In a further aspect of this invention, a rifle bore having a reduced diameter im6ay ;alzo have a plurality of rifling grooves, and preferably the rate of twist of the rifling grooves is at least one twist in 30cms or less. Again, the "i'r inventor has found that significant improvements result when S the rate of twist is one twist between 30 and Contrary to expectations, it has been found that a smaller diameter barrel still allows the projectile to traverse through the barrel with an interference fit without causing damage to the internal surface of the barrel. There is no noticeable drop in muzzle velocity, and the projectile has an improved sectional density and ballistic coefficient.

.2.9 The improved sectional density of the "extruded" bullet increases its penetration in target material of uniform density by approximately In one example of this invention, a conventional 0.22 calibre rifle barrel was replaced by a non-conventional 0.17 calibre rifle barrel. This rifle retained its conventional 0.22 calibre firing chamber which was designed for a 0.22 calibre long cartridge containing a 29grn weight projectile. When fired from the unconventional 0.17 calibre barrel a muzzle velocity of approximately 1200 F.P.S. (369 metres per second) was achieved. This muzzle velocity is not vastly different from a conventional 0.22 rifle barrel, however it was found that the projectile (being lead or plated lead) was deformed -s such that there was a reduction in diameter and an increase -2- L ~c

I,

I i in projectile length as it traversed through the 0.17 calibre barrel. This alone gave it an improved ballistic characteristic such as a flatter trajectory and a greater retained energy at the target. It is believed that some of this effect was achieved by avoiding loss of gas around the circumference of the projectile during its passage through the barrel, and that this at least partly made up for the energy required to cause deformation of the projectile.

In another experiment, the 0.17 calibre barrel was provided with a rifling twist of 1 twist per 25cms compared with the conventional one twist per 39cms. Obviously, this provided a greater rate of spin to the elongated projectile, and this also improved the trajectory profile. Further, the impact PiT force of the projectile on the target was increased.

Further tests have been conducted with a twist rate of one ~ro turn per 20cms in a 0.17 calibre rifle barrel that had a firing chamber to suit a 0.22 long rifle cartridge with 36grm bullets. The penetration of the projectile from this rifle which was tested by firing it into a material of uniform 0 o density showed that the penetration rate was 50% greater than the standard 0.22 calibre long rifle cartridge when fired from the standard 0.22 calibre rifle.

S: The extra spin created on the 36grm bullet in the one in twist rate is of the order of 50% greater than with the conventional one in 30cm twist rate. This increased spin results in a projectile having a much greater force of impact. The main advantage of increased projectile penetration of approximately 50%, and an increased projectile spin rate of over 50% is the improved trajectory of the projectile, together with improved impact force.

In addition to the above tests, the applicant has also used a 0.195 calibre rifle bore with a cartridge loaded with a projectile. The rate of twist of the rifling grooves was one twist per 30cms by comparison to the conventional one twist per 39cms. Although there is less deformation of the -3r i.

projectile within the rifle barrel during its movement therethrough, a much better than conventional ballistic coefficient was achieved which included a much flatter trajectory.

To the applicant's surprise, a careful inspect of the barrels having a reduced bore diameter with respect to the nominal size of the cartridge and projectile after having projectiles fired through it did not indicate any lead deposit on the interior surface of the barrel, and if conventional wax coated lead bullets are used, then it is anticipated that lead deposit within the barrel will be almost non-existent.

Further, it is anticipated that the inventive concept described above can also be used to reduce the projectile diameter during firing of parent cartridges such as the 0.22 rim fire magnum which use projectiles other than the jacketed type. The advantages of increased projectile spin rate, sectional density and ballistic coefficient are directly related to the smaller diameter of the projectile once fired through the rifle.

It is expected that these advantages will be obtained with the use of lubricated lead, plated lead projectiles, including the use of these projectiles with the centre fire cartridges having a lower velocity range. These cartridges are typical of those used in lever action or brake action firearms. In all of these examples, the life of the rifle barrel will be equivalent to conventional diameter bore rifle barrels.

Claims

1. A rifle having a firing chamber to receive a cartridge and projectile of a nominal size, said firing chamber coupled to a rifle barrel, the diameter of the bore of said rifle barrel being smaller than said nominal size of said projectile by at least 8% such that during discharge said projectile is reduced in diameter upon travelling through said rifle bore, and wherein said bore of the rifle barrel is provided with a plurality of rifling grooves, the rate of twist of said rifling grooves being at least one twist in 30cm or less.

2. A rifle according to claim 1 wherein the diameter of said bore is smaller than said nominal size by between 8-25%.

3. A rifle according to claim 1 or claim 2 wherein said rate of twist of said rifling grooves is one twist between and A rifle according to any one of the preceding claims substantially as hereinbefore described. Dated this 29th day of January, 1996. t I ARTHUR WILLIAM LANGSFORD By his Patent Attorneys MADDERNS 411/ i t 0 CI, ABSTRACT This invention relates to a rifle having a firing chamber to receive a cartridge and projectile of nominal size, said firing chamber coupled to a rifle barrel, the diameter of the bore of said rifle barrel being smaller than said nominal size of said projectile such that during discharge said projectile is reduced in diameter upon travelling through said rifle bore.