# US 7,743,705 B2 · Propellant sealing system for stackable projectiles

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- Number: US 7,743,705 B2
- Document ID: US7743705B2
- Status: Granted
- Kind: B2
- Application number: 12/280,108
- Filed: 2007-02-21
- Published: 2009-04-02
- Granted: 2010-06-29
- Earliest claimed: 2006-02-21
- Assignees: Metal Storm Limited
- Inventors: Sean P. O'Dwyer
- Web page: https://patentgrep.com/patent/US7743705B2

## CPC

- F42B 5/035: {the cartridge or barrel assembly having a plurality of axially stacked projectiles each having a separate propellant charge}
- F42B: EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION (explosive compositions C06B; fuzes F42C; blasting F42D)

## Abstract

A projectile for use in a barrel with stacked projectiles, particularly for a weapon which can be reloaded by a user in the field. The projectile includes a chamber containing a propellant charge, with an exit from the chamber for release of propulsion gases into the barrel. A seal blocks the exit and is opened by ignition of the propellant within the chamber but is resistant to gases produced by ignition of propellant in other projectiles in the barrel. The exit and seal are provided in a range of different forms. The exit may be an aperture in a wall of the chamber with the seal as a moveable barrier, such as a valve-like structure, for example. The seal may also include a rupturable or deformable barrier across the aperture. Alternatively the seal is a thin barrier around the charge such as a wax coating and the exit involves a disintegrable character of the barrier. The seal may also be an inherent property of the geometry of the chamber.

## Claims

### Claim 1

A projectile for use in a barrel with a plurality of stacked projectiles, including:
a chamber containing a propellant charge for the projectile,
an exit from the chamber for release of propulsion gases into the barrel when the propellant is ignited to fire the projectile, the exit including a sealing surface,
a seal blocking the exit by sealing against the sealing surface of the chamber, wherein the seal is opened by ignition of the propellant within the chamber but is resistant to propulsion gases from other projectiles in the barrel and is forced further into engagement with the sealing surface by pressure from propulsion gases from other projectiles in the barrel, and
a retainer engaging the seal into engagement with the sealing surface,
wherein the seal is deformable between a closed condition and an open condition by deformation, and
wherein the retainer includes a supporting stop for confining the deformation of the seal.

### Claim 2 (depends on 1)

A projectile according to claim 1 wherein the retainer engages the chamber within the exit.

### Claim 3 (depends on 2)

A projectile according to claim 2 wherein the retainer is annular and propulsion gases pass through the retainer.

### Claim 4 (depends on 1)

A projectile according to claim 1 wherein the retainer engages with the chamber external to the exit.

### Claim 5 (depends on 4)

A projectile according to claim 4 wherein the retainer comprises a jacket.

### Claim 6 (depends on 1)

A projectile according to claim 1 wherein part of the seal ruptures.

### Claim 7 (depends on 1)

A projectile according to claim 1 wherein the seal deforms to release propulsion gases after a predetermined pressure has been reached.

### Claim 8 (depends on 1)

A projectile according to claim 1 wherein the seal includes a disc and a crushable member and the crushable member is located between the disc and the retainer with the crushable member engaging the retainer.

### Claim 9 (depends on 8)

A projectile according to claim 8 wherein the crushable member is a spring.

### Claim 10 (depends on 1)

A projectile according to claim 1 wherein the retainer engages the chamber by a threaded engagement, whereby the threaded engagement is advanced to increase the engagement between the seal and the sealing surface.

### Claim 11 (depends on 1)

A projectile according to claim 1 wherein the exit includes one or more vents which are blocked by the seal.