GB2357824A

GB2357824A - Pneumatic small arms ammunition

Info

Publication number: GB2357824A
Application number: GB0004780A
Authority: GB
Inventors: Mark Tassell
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-03-01
Filing date: 2000-03-01
Publication date: 2001-07-04
Anticipated expiration: 2020-03-01
Also published as: GB2357824B; GB0004780D0

Abstract

A pneumatic round of ammunition comprising of a body 1, sealed at both ends with valves 5 and 7, compartmentalised internally into two chambers by a piston 10 urged a forward 'sealed position' by the rear valve return spring 8. Both chambers being filled with, and being capable of holding an equal pressure of gas/air. When the rear valve 7 is dislodged upon firing, an in-balance in pressure is then created within the round and the piston is forcibly moved rearwards under the pressure of gas/air within the front chamber, thus opening the discharging passage 11 and releasing the gas/air charge held within, behind the projectile. The bush 9 allows gas to flow freely therethrough.

Description

2357824 Pneumatic small arms ammunition

This invention relates to rounds of ammunition for use in either small arms or specially adapted air weapons. Where instead of a pyrotechnic charge, a charge of compressed air gas is used to propel a projectile. Cartridges of this nature do exist indeed within the fields of small arms and air weapons, though they may be used it is felt they may not be as successful or reliable as possible. The cartridge described within this application is designed with a new approach, which alleviates the main problems associated with current cartridges. These are either very complex designs or poor energy deliverance. With a complex design it becomes necessary when working on a small item to ensure tolerances are met and components exactly match and inter relate perfectly. This is possible to achieve on modem computer numerically controlled (CNC) machines but when mass production is required as in the case of these cartridges difficulties do arise, so a more simplistic design would facilitate mass production. It has been noted, with certain designs, that upon detonation of the cartridge the valve stem either interferes with the passage of air / gas partially blocking it's transfer ports or prematurely closes it's valve without a total discharge. This is undesirable in that there is limited energy available to the projectile in a cartridge and any residue / restriction is wasted energy. This by nature of design would also lead to inconsistencies in velocity and energy of the projectile.

The idea described herein is to provide a new design of air / gas cartridge with fewer components and improved charge deliverance. Unlike pyrotechnic cartridges where the projectile is seated in the mouth of the cartridge, it's necessary to enclose the end of on air gas cartridge with a valve and abut this to the projectile. If a cartridge were to be fitted with a valve stem that upon firing would emerge from within its cartridge then this would protrude within the projectile holder and would impede air / gas flow as previously mentioned. To overcome this the valve stem / seal would have to retreat from it's seating to allow for discharging. It is in this design that I would now like to describe an example.

The cartridge is manufactured with two valves, fitted on opposing ends with a slideable, sealed divider (piston) fitted to one end (see Fig 1). The piston and bottom valve are held apart by a small bias spring located on a stud on the valve and within a central chamber on the piston. Charging is carried out using pre-compressed air / gas from a cylinder via a specially manufactured adapter. During charging equal pressure is delivered into the separate chambers using the air / gas pressure to open and displace the valves. These are returned by the small bias spring fitted between the piston and valve which closes and seals the cartridge once again. Once charged it is now possible to load the projectile within its holder, once completed it is ready to use. To discharge the cartridge its rear needs to be struck with a firing pin. This would then unseat it allowing air / gas to leak out and discharge the rear chamber. When this takes place an imbalance is formed within the cartridge and the piston is forced to retreat, releasing its charge directly behind the projectile.

This design of cartridge could also produce benefits with fewer components. An increase in internal free air would allow a lower working pressure to be used to attain similar velocities. This would in turn result in less fatigue on components and a longer working life, With this it also becomes possible to manufacture some or all components from specialist plastics resins which become desirable to a mass production market.

Figure 1 Shows a sectional view through the cartridge Figure 2 A cross section through the cartridge to show anti tip bush turned on the valve stem.

As can be seen in Fig 1 the cartridge consists of eight components. The first, the outer case (1), or body is turned from brass or another nonporous metal / plastic. It has a hole centrally bored in it's base (12) to create a transfer port and relieved on its inner surfaces at such an angle to compliment the rear valve (7). The other end of the body is internally threaded at its mouth to accept the end sealing plug (2). The plug has a groove turned around the base of the thread to accept an 'o' ring in order to make an air / gas tight seal upon the cartridge body. The plug is bored through centrally creating a transfer port, which is internally relieved at an angle complementary to the valve stem front seal (5), so as to create the valve seat. From Fig 1 the valve stem (4) is also shown running through the centre of the cartridge and fitted with two turned bushes (9 & 10) of a size to become a sliding fit inside the cartridge. The rear bush is turned with a groove to accept an 'o' ring which will compartmentalise the cartridge with an air / gas tight seal. The front bush is sectioned as shown in Fig 2 to allow free flow of air, it's only purpose being to prevent the tipping of the valve stem during charging discharging. The extreme front of the valve stem is turned with a groove around it's circumference to accept an 'o' ring (5) which when seated against the end plug creates an air / gas tight seal. The opposing end of the valve stem is drilled centrally with a hole to accept the valve return spring (8) of the base valve. The base valve (7) being a turned disc with an angle complementary to the valve seat. The disc also has a groove turned around it's circumference 1/3 back from its front (smallest dia.) to accept an 'o' ring (6) which will create an air / gas tight seal against the valve seat. The rear end of this valve disc is reduced in size to fit and locate upon its valve return spring (8).

7_ 12

Claims

1. A round of ammunition designed specifically to be charged with air/gas under pressure. Consisting of a casing usually cylindrical, divided radially into two separate pressure chambers by a slideable piston. The pistons front extremity is fitted with a means of sealing the ftont intake - exhaust valve, when in its furthest forward position or normal position of the piston in the charged - uncharged state. The small bias applied by the rear valve return spring is used to return the piston to the position after charging - discharging. The rear of the piston is fitted with a means of scaling radially to the casing wall, to create and separate the chambers. The opposing chamber to which the piston front seal extends into is fitted with an independent valve axially supported by a recess in the rear of the piston and the valve seat itseK it is by this means the rear intake - exhaust valve is sealed.

2. A round of ammunition as in 1 whereby air/gas is forced under pressure into separated chambers from opposing ends by means of a pre compressed source (not described herein)

3. A round of ammunition as in 1 and 2 whereby the forward discharge valve is held closed by an equal pressure of air/gas acting upon the pistons rear surfaces in opposing directions and a small bias being applied by the rear valve return spring.

I-C

2. A round of ammunition as in 1 whereby air/gas is forced under pressure into the separated chambers simultaneously from opposing ends by means of a pre-compressed source. (Not described herein) 3. A round of ammunition as in 1 and 2 whereby the forward discharge valve is held closed by an equal pressure of air/gas acting upon the pistons rear surflices in opposing directions and a small bias being applied by the rear valve return spring.

Amendments to the claims have been filed as follows 1, A round of ammunition designed specifically to be charged with gas/air under pressure comprising a casing having at opposite ends thereof openings which provide front and rear charging and discharging ports for said gas/air, the interior of the casing being divided into two separate chambers by a moveable piston capable of moving rearwards to allow charging or discharging through the front port but generally being held in it's forward position to provide a seal for the front port, the piston being held in it's forward position by a spring acting between the piston and a valve of the rear charging and discharging port, and the piston sealing the two chambers from one and other so that each chamber can only receive gas/air under pressure through it's own charging / discharging port.