Propellant sealing system for stackable projectiles
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.
1. A projectile for use in a barrel with a plurality of stacked projectiles, including:
a chamber containing a propellant charge for the projectile, the chamber including a sealing surface,
an exit from the chamber for release of propulsion gases into the barrel when the propellant is ignited to fire the projectile,
a deformable 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 ruptured by ignition of the propellant within the chamber along lines of weakness formed by grooves on a surface of the seal external to the chamber.
2. A projectile according to claim 1 wherein the lines of weakness are configured to form a throttle.
3. A projectile according to claim 1 wherein the cross sectional shape of the lines of weakness include radiuses.
4. A projectile according to claim 1 wherein the lines of weakness include two or more intersecting grooves.
5. A projectile according to claim 4 wherein the lines of weakness are equal in length and bisect each other to form leaves.
6. A projectile according to claim 1 wherein the retainer is a separate component and engages the chamber within the exit.
7. A projectile according to claim 1 wherein the retainer is a separate component and engages with the chamber external to the exit.
8. A projectile according to claim 1 wherein the retainer is annular and propulsion gases pass through the retainer.
9. A projectile according to claim 1 wherein the seal is a disc.
10. A projectile according to claim 1 wherein the retainer is a separate component and engages with the chamber by a threaded engagement.
11. A projectile according to claim 10 wherein the retainer includes slots or a hexagonal surface for engaging a tool for advancing the threaded engagement.