Air operated projectile firing apparatus

A firearm such as a rifle or the like having an air ignition system for firing a round of ammunition, said ammunition comprising a projectile and a propellant ignitable by surface contact with high temperature air, said firearm comprising:

• receiver means for supporting the operational mechanism of said firearm;
• a source of high temperature air for ignition of the propellant by surface contact therewith comprising air compression cylinder means mounted on said receiver means, piston means movably mounted in said cylinder means for movement between a retracted position and an extended position during an air compression stroke, piston driving spring means for driving said piston during a compression stroke;
• sear means for latching said piston means in the retracted position;
• trigger means for releasing said sear means to initiate a compression stroke;
• barrel means mounted on said receiver means and extending parallelly to said compression chamber means for guiding the projectile from said device after ignition of the propellant;
• ammunition loading means provided adjacent the rear of said barrel means;
• separate movable breech means separate from and movably mounted on said receiver means between said barrel means and said loading means for movement between a firing position in line with said barrel means and a loading position spaced transversely of said barrel means;
• obturation means provided on said breech means and being movable therewith;
• firing chamber means provided in said breech means within said obturation means by an enlarged chamber adapted to surround the propellant;
• high temperature air delivery means connecting said air compression cylinder means to said firing chamber means to deliver high temperature air from said compression cylinder means to said firing chamber means for ignition of the propellant by surface contact therewith;
• and flow control means within the firearm associated with said air delivery means permitting flow of high temperature air from said air compression cylinder means to said firing chamber means during a compression stroke and preventing flow of high temperature propellant gases from said firing chamber means to said air compression cylinder means after ignition of said propellant.

A firearm such as a rifle or the like having an air ignition system for firing a round of ammunition, said round of ammunition comprising a projectile having a propellant ignitable by surface contact with high temperature air associated therewith, said firearm comprising:

• receiver means for supporting the operational mechanism of the firearm;
• barrel means having a bore mounted on said receiver means for guiding the projectile from the firearm after ignition of the propellant;
• ammunition holding means within said firearm at the rear of said barrel means for holding a projectile and associated propellant in a firing position aligned with said bore in said barrel means;
• firing chamber means adapted to receive and surround the propellant portion of the ammunition in the firing position;
• a source of high temperature air within the firearm having a temperature at which the propellant is ignitable by surface contact therewith comprising air compression means and piston means movable therein to compress air during an air compression stroke, piston driving spring means associated with said piston means to drive said piston means from a retracted position to an extended position during an air compression stroke;
• relatively movable breech means movably mounted in said receiver means at the rear of said barrel means and at least a portion of said breech means being movable between a firing position and a loading position and said breech means connecting said source to said firing chamber means in the firing position;
• sear means to latch said piston means in the retracted position;
• trigger means to selectively release said sear means to initiate an air compression stroke;
• cocking means to move said piston means to the retracted position against the bias of said piston driving spring means;
• air delivery means for delivering high temperature air from said air compression means extending through at least a portion of said breech means and terminating in said firing chamber means;
• flow control means within the firearm separate from the ammunition permitting flow of high temperature air from said air compression means to said firing chamber means and preventing flow of high temperature fluids from said firing chamber means to said air compression means after ignition of said propellant;
• said firing chamber means comprising an area of abutting engagement between said projectile and said ammunition holding means;
• an enlarged chamber located rearwardly of the area of abutting engagement between said projectile and said ammunition holding means;
• and
• obturation means for confining propellant gases to said firing chamber means formed in part on said ammunition holding means and in part on said air compression means, and being located between said flow control means and said bore in said barrel means.

A firearm such as a rifle or the like having an air ignition system for firing a round of ammunition, said round of ammunition comprising a projectile having a propellant ignitable by surface contact with high temperature air associated therewith, said firearm comprising:

• receiver means for supporting the operational mechanism of the firearm;
• barrel means having a bore mounted on said receiver means for guiding the projectile from the firearm after ignition of the propellant;
• ammunition holding means within said firearm at the rear of said barrel means for holding a projectile and associated propellant in a firing position aligned with said bore in said barrel means;
• firing chamber means adapted to receive and surround the propellant portion of the ammunition in the firing position;
• a source of high temperature air within the firearm having a temperature at which the propellant is ignitable by surface contact therewith comprising air compression means and piston means movable therein to compress air during an air compression stroke, piston driving spring means associated with said piston means to drive said piston means from a retracted position to an extended position during an air compression stroke;
• relatively movable breech means movably mounted in said receiver means at the rear of said barrel means and at least a portion of said breech means being movable between a firing position and a loading position and said breech means connecting said source to said firing chamber means in the firing position;
• sear means to latch said piston means in the retracted position;
• trigger means to selectively release said sear means to initiate an air compression stroke;
• cocking means to move said piston means to the retracted position against the bias of said piston driving spring means;
• air delivery means for delivering high temperature air from said air compression means extending through at least a portion of said breech means and terminating in said firing chamber means;
• flow control means within the firearm separate from the ammunition permitting flow of high temperature air from said air compression means to said firing chamber means and preventing flow of high temperature fluids from said firing chamber means to said air compression means after ignition of said propellant;
• said ammunition holding means comprises bore means having a first portion substantially corresponding in diameter to said bore in the barrel means and to a portion of said projectile;
• and
• having a second portion enlarged relative to said first portion and located rearwardly thereof and providing abutment means engageable with an enlarged other portion of said projectile located rearwardly of the first mentioned portion of the projectile.

A firearm such as a rifle or the like having an air ignition system for firing a round of ammunition, said round of ammunition comprising a projectile having a propellant ignitable by surface contact with high temperature air associated therewith, said firearm comprising:

• receiver means for supporting the operational mechanism of the firearm;
• barrel means having a bore mounted on said receiver means for guiding the projectile from the firearm after ignition of the propellant;
• ammunition holding means within said firearm at the rear of said barrel means for holding a projectile and associated propellant in a firing position aligned with said bore in said barrel means;
• firing chamber means adapted to receive and surround the propellant portion of the ammunition in the firing position;
• a source of high temperature air within the firearm having a temperature at which the propellant is ignitable by surface contact therewith comprising air compression means and piston means movable therein to compress air during an air compression stroke, piston driving spring means associated with said piston means to drive said piston means from a retracted position to an extended position during an air compression stroke;
• relatively movable breech means movably mounted in said receiver means at the rear of said barrel means and at least a portion of said breech means being movable between a firing position and a loading position and said breech means connecting said source to said firing chamber means in the firing position;
• sear means to latch said piston means in the retracted position;
• trigger means to selectively release said sear means to initiate an air compression stroke;
• cocking means to move said piston means to the retracted position against the bias of said piston driving spring means;
• air delivery means for delivering high temperature air from said air compression means extending through at least a portion of said breech means and terminating in said firing chamber means;
• flow control means within the firearm separate from the ammunition permitting flow of high temperature air from said air compression means to said firing chamber means and preventing flow of high temperature fluids from said firing chamber means to said air compression means after ignition of said propellant;
• said flow control means comprising a valve assembly;
• and
• said valve assembly being mounted in at least one portion of said breech means.

A firearm such as a rifle of the like having an air ignition system for firing a round of ammunition, said round of ammunition comprising a projectile having a propellant ignitable by surface contact with high temperature air associated therewith, said firearm comprising:

• receiver means for supporting the operational mechanism of the firearm;
• barrel means having a bore mounted on said receiver means for guiding the projectile from the firearm after ignition of the propellant;
• ammunition holding means within said firearm at the rear of said barrel means for holding a projectile and associated propellant in a firing position aligned with said bore in said barrel means;
• firing chamber means adapted to receive and surround the propellant portion of the ammunition in the firing position;
• a source of high temperature air within the firearm having a temperature at which the propellant is ignitable by surface contact therewith comprising air compression means and piston means movable therein to compress air during an air compression stroke, piston driving spring means associated with said piston means to drive said piston means from a retracted position to an extended position during an air compression stroke;
• relatively movable breech means movably mounted in said receiver means at the rear of said barrel means and at least a portion of said breech means being movable between a firing position and a loading position and said breech means connecting said source to said firing chamber means in the firing position;
• sear means to latch said piston means in the retracted position;
• trigger means to selectively release said sear means to initiate an air compression stroke;
• cocking means to move said piston means to the retracted position aganst the bias of said piston driving spring means;
• air delivery means for delivering high temperature air from said air compression means extending through at least a portion of said breech means and terminating in said firing chamber means;
• flow control means within the firearm separate from the ammunition permitting flow of high temperature air from said air compression means to said firing chamber means and preventing flow of high temperature fluids from said firing chamber means to said air compression means after ignition of said propellant;
• at least one portion of said breech means being attached to said air compression means.

A firearm having an air ignition system for firing a projectile having an associated propellant capable of being ignited by surface contact with high temperature air comprising:

• barrel means for guiding the projectile from within the firearm after ignition of the propellant;
• ammunition holding means within the firearm for holding the projectile in a firing position within the firearm;
• a source of high temperature air within the firearm having a temperature at which the propellant is ignitable by surface contact therewith;
• air delivery means within the firearm for delivering high temperature air from said source to said propellant at a temperature at which the propellant is ignitable by surface contact therewith;
• and
• relatively movable breech means within the firearm interposed between said ammunition holding means and said source and being movable relative to said source between a firing position connecting said ammunition holding means to said source and a loading position,
• a portion of said movable breech means surrounding said propellant in the firing position and defining firing chamber means to which the high temperature air is delivered from said source,
• and obturation means for confining propellant gases to said firing chamber means formed by another portion of said movable breech means and said ammunition holding means in the firing position.

A firearm having an air ignition system for firing a projectile having a propellant associated therewith ignitable by surface contact with high temperature air, said firearm comprising:

• a source of high temperature air having a temperature at which the propellant is ignitable by surface contact therewith;
• barrel means for guiding the projectile from the firearm after ignition of the propellant;
• breech means connecting said barrel means to said source;
• means supporting at least a portion of said breech means and said barrel means for relative movement between a loading position and a firing position;
• obturation means effective between said breech means and said barrel in the firing position, said obturation means comprising an enlarged chamber on one means and a projecting plug on the other means, said chamber and said plug being correspondingly shaped for mating engagement in the firing position;
• firing chamber means defined by said chamber and said plug in the firing position and comprising an enlarged chamber surrounding the propellant;
• and
• passage means extending from said source through said breech means to said firing chamber means to deliver high temperature air to said firing chamber for ignition of the propellant.

A firearm having an air ignition system for firing ammunition of the type having a projectile and a propellant attached thereto, said propellant being capable of being ignited by surface contact with high temperature air, said firearm containing separately of said ammunition:

• barrel means for guiding the projectile from the apparatus,
• ammunition holding means within the firearm for holding the ammunition in a firing position within the firearm during ignition of the propellant, including abutment means engageable with the ammunition to hold the ammunition against movement from the firing position until a predetermined shot start force is exerted by the propellant gases after ignition of the propellant
• firing chamber means within the firearm surrounding said propellant in the firing position,
• air compression means within the firearm for obtaining high temperature air capable of igniting the propellant in the firing chamber,
• breech means within the firearm interposed between said barrel means and said air compression means,
• obturation means provided on said breech means for sealing said firing chamber means, prior to ignition of the propellant and confining the propellant gases to said firing chamber means
• air delivery means within the firearm for delivering the high temperature air to the firing chamber means from the air compression means for ignition of the propellant by surface contact with the high temperature air,
• and flow control means within the firearm associated with said air delivery means permitting flow of high temperature air from said air compression cylinder means to said firing chamber during a compression stroke and preventing flow of high temperature propellant gases from said firing chamber to said air compression cylinder means after ignition of said propellant.

A firearm having an air ignition system for firing ammunition having a projectile and an associated propellant capable of being ignited by surface contact with high temperature air comprising within the firearm and separate from the ammunition:

• barrel means having a bore for guiding the projectile from the firearm after ignition of said propellant;
• movable ammunition holding means for receiving the projectile and the propellant in a loading position and for carrying the projectile and the propellant from the loading position to the firing position and for holding the projectile and the propellant in a firing position in alignment with said bore in said barrel means prior to ignition of said propellant;
• a source of high temperature air having a temperature at which the propellant is ignitable by surface contact therebetween;
• firing chamber means formed about the propellant in the firing position;
• air delivery means connecting said source to said firing chamber means to deliver high temperature air from said source to said firing chamber at a temperature at which the propellant is ignitable by surface contact therebetween;
• obturation means effective in the firing position between the barrel means and the ammunition holding means and between the air delivery means and the ammunition holding means;
• valve means associated with said air delivery means to close said firing chamber means relative to said source after delivery of the high temperature air to prevent flow of fluids from the firing chamber to the source after ignition of said propellant;
• said obturation means comprising plug means and said valve means being mounted in said plug means.

A firearm having an air ignition system for firing ammunition having a projectile and an associated propellant capable of being ignited by surface contact with high temperature air comprising within the firearm and separate from the ammunition:

• barrel means having a bore for guiding the projectile from the firearm after ignition of said propellant;
• movable ammunition holding means for receiving the projectile and the propellant in a loading position and for carrying the projectile and the propellant from the loading position to the firing position and for holding the projectile and the propellant in a firing position in alignment with said bore in said barrel means prior to ignition of said propellant;
• a source of high temperature air having a temperature at which the propellant is ignitable by surface contact therebetween;
• firing chamber means formed about the propellant in the firing position;
• air delivery means connecting said source to said firing chamber means to deliver high temperature air from said source to said firing chamber at a temperature at which the propellant is ignitable by surface contact therebetween;
• obturation means effective in the firing position between the barrel means and the ammunition holding means and between the air delivery means and the ammunition holding means;
• valve means associated with said air delivery means to close said firing chamber means relative to said source after delivery of the high temperature air to prevent flow of fluids from the firing chamber to the source after ignition of said propellant;
• and
• movable breech means in said firearm;
• said valve means being mounted in said movable breech means.

A firearm having an air ignition system for firing ammunition having a projectile and an associated propellant capable of being ignited by surface contact with high temperature air comprising within the firearm and separate from the ammunition:

• barrel means having a bore for guiding the projectile from the firearm after ignition of said propellant;
• movable ammunition holding means for receiving the projectile and the propellant in a loading position and for carrying the projectile and the propellant from the loading position to the firing position and for holding the projectile and the propellant in a firing position in alignment with said bore in said barrel means prior to ignition of said propellant;
• a source of high temperature air having a temperature at which the prolellant is ignitable by surface contact therebetween;
• firing chamber means formed about the propellant in the firing position;
• air delivery means connecting said source to said firing chamber means to deliver high temperature air from said source to said firing chamber at a temperature at which the propellant is ignitable by surface contact therebetween;
• obturation means effective in the firing position between the barrel means and the ammunition holding means and between the air delivery means and the ammunition holding means;
• valve means associated with said air delivery means to close said firing chamber means relative to said source after delivery of the high temperature air to prevent flow of fluids from the firing chamber to the source after ignition of said propellant;
• and
• means for separating said air compression means from said barrel means for loading ammunition.

A firearm having an air ignition system for firing ammunition having a projectile and an associated propellant capable of being ignited by surface contact with high temperature air comprising within the firearm and separate from the ammunition:

• barrel means having a bore for guiding the projectile from the firearm after ignition of said propellant;
• movable ammunition holding means for receiving the projectile and the propellant in a loading position and for carrying the projectile and the propellant from the loading position to the firing position and for holding the projectile and the propellant in a firing position in alignment with said bore in said barrel means prior to ignition of said propellant;
• a souce of high temperature air having a temperature at which the propellant is ignitable by surface contact therebetween;
• firing chamber means formed about the propellant in the firing position;
• air delivery means connecting said source to said firing chamber means to deliver high temperature air from said source to said firing chamber at a temperature at which the propellant is ignitable by surface contact therebetween;
• obturation means effective in the firing position between the barrel means and the ammunition holding means and between the air delivery means and the ammunition holding means;
• valve means associated with said air delivery means to close said firing chamber means relative to said source after delivery of the high temperature air to prevent flow of fluids from the firing chamber to the source after ignition of said propellant;
• and
• means for separating said air compression means from said barrel means by movement therebetween.

A firearm having an air ignition system for firing ammunition having a projectile and an associated propellant capable of being ignited by surface contact with high temperature air comprising within the firearm and separate from the ammunition:

• barrel means having a bore for guiding the projectile from the firearm after ignition of said propellant;
• movable ammunition holding means for receiving the projectile and the propellant in a loading position and for carrying the projectile and the propellant from the loading position to the firing position and for holding the projectile and the propellant in a firing position in alignment with said bore in said barrel means prior to ignition of said propellant;
• a source of high temperature air having a temperature at which the propellant is ignitable by surface contact therebetween;
• firing chamber means formed about the propellant in the firing position;
• air delivery means connecting said source to said firing chamber means to deliver high temperature air from said source to said firing chamber at a temperature at which the propellant is ignitable by surface contact therebetween;
• obturation means effective in the firing position between the barrel means and the ammunition holding means and between the air delivery means and the ammunition holding means,
• valve means associated with said air delivery means to close said firing chamber means relative to said source after delivery of the high temperature air to prevent flow of fluids from the firing chamber to the source after ignition of said propellant;
• and
• means for separating said air compression means from said barrel means by axial movement.

A firearm having an air ignition system for firing ammunition having a projectile and an associated propellant capable of being ignited by surface contact with high temperature air comprising within the firearm and separate from the ammunition:

• barrel means having a bore for guiding the projectile from the firearm after ignition of said propellant;
• movable ammunition holding means for receiving the projectile and the propellant in a loading position and for carrying the projectile and the propellant from the loading position to the firing position and for holding the projectile and the propellant in a firing position in alignment with said bore in said barrel means prior to ignition of said propellant;
• a source of high temperature air having a temperature at which the propellant is ignitable by surface contact therebetween;
• firing chamber means formed about the propellant in the firing position;
• air delivery means connecting said source to said firing chamber means to deliver high temperature air from said source to said firing chamber at a temperature at which the propellant is ignitable by surface contact therebetween;
• obturation means effective in the firing position between the barrel means and the ammunition holding means and between the air delivery means and the ammunition holding means;
• valve means associated with said air delivery means to close said firing chamber means relative to said source after delivery of the high temperature air to prevent flow of fluids from the firing chamber to the source after ignition of said propellant;
• and
• means for separating said air compression means from said barrel means by relative axial movement between said air compression means and said barrel means.

A firearm having an air ignition system for firing ammunition having a projectile and an associated propellant capable of being ignited by surface contact with high temperature air comprising within the firearm and separate from the ammunition:

• barrel means having a bore for guiding the projectile from the firearm after ignition of said propellant;
• movable ammunition holding means for receiving the projectile and the propellant in a loading position and for carrying the projectile and the propellant from the loading position to the firing position and for holding the projectile and the propellant in a firing position in alignment with said bore in said barrel means prior to ignition of said propellant;
• a source of high temperature air having a temperature at which the propellant is ignitable by surface contact therebetween;
• firing chamber means formed about the propellant in the firing position;
• air delivery means connecting said source to said firing chamber means to deliver high temperature air from said source to said firing chamber at a temperature at which the propellant is ignitable by surface contact therebetween;
• obturation means effective in the firing position between the barrel means and the ammunition holding means and between the air delivery means and the ammunition holding means;
• valve means associated with said air delivery means to close said firing chamber means relative to said source after delivery of the high temperature air to prevent flow of fluids from the firing chamber to the source after ignition of said propellant;
• and
• movable breech means intermediate said air compression means and said barrel means;
• and
• means for separating said air compression means from said barrel means by movement of said movable breech means intermediate said air compression means and said barrel means.

A firearm having an air ignition system for firing ammunition having a projectile and an associated propellant capable of being ignited by surface contact with high temperature air comprising within the firearm and separate from the ammunition:

• barrel means having a bore for guiding the projectile from the firearm after ignition of said propellant;
• movable ammunition holding means for receiving the projectile and the propellant in a loading position and for carrying the projectile and the propellant from the loading position to the firing position and for holding the projectile and the propellant in a firing position in alignment with said bore in said barrel means prior to ignition of said propellant;
• a source of high temperature air having a temperature at which the propellant is ignitable by surface contact therebetween;
• firing chamber means formed about the propellant in the firing position;
• air delivery means connecting said source to said firing chamber means to deliver high temperature air from said source to said firing chamber at a temperature at which the propellant is ignitable by surface contact therebetween;
• obturation means effective in the firing position between the barrel means and the ammunition holding means and between the air delivery means and the ammunition holding means;
• valve means associated with said air delivery means to close said firing chamber means relative to said source after delivery of the high temperature air to prevent flow of fluids from the firing chamber to the source after ignition of said propellant;
• and
• means for separating said air compression means from said barrel means by movement transverse to the longitudinal axis of said barrel means.

A firearm having an air ignition system for firing ammunition having a projectile and an associated propellant capable of being ignited by surface contact with high temperature air comprising within the firearm and separate from the ammunition:

• barrel means having a bore for guiding the projectile from the firearm after ignition of said propellant;
• movable ammunition holding means for receiving the projectile and the propellant in a loading position and for carrying the projectile and the propellant from the loading position to the firing position and for holding the projectile and the propellant in a firing position in alignment with said bore in said barrel means prior to ignition of said propellant;
• a source of high temperature air having a temperature at which the propellant is ignitable by surface contact therebetween;
• firing chamber means formed about the propellant in the firing position;
• air delivery means connecting said source to said firing chamber means to deliver high temperature air from said source to said firing chamber at a temperature at which the propellant is ignitable by surface contact therebetween;
• obturation means effective in the firing position between the barrel means and the ammunition holding means and between the air delivery means and the ammunition holding means;
• valve means associated with said air delivery means to close said firing chamber means relative to said source after delivery of the high temperature air to prevent flow of fluids from the firing chamber to the source after ignition of said propellant;
• movable breech means intermediate said air compression means and said barrel means;
• and
• means for separating said air compression means from said barrel means by relative movement between said air compression means and said barrel means, and by movement of the movable breech means intermediate said air compression means and said barrel means.

A firearm having an air ignition system for firing ammunition having a projectile and an associated propellant capable of being ignited by surface contact with high temperature air comprising within the firearm and separate from the ammunition:

• barrel means having a bore for guiding the projectile from the firearm after ignition of said propellant;
• movable ammunition holding means for receiving the projectile and the propellant in a loading position and for carrying the projectile and the propellant from the loading position to the firing position and for holding the projectile and the propellant in a firing position in alignment with said bore in said barrel means prior to ignition of said propellant;
• a source of high temperature air having a temperature at which the propellant is ignitable by surface contact therebetween;
• firing chamber means formed about the propellant in the firing position;
• air delivery means connecting said source to said firing chamber means to deliver high temperature air from said source to said firing chamber at a temperature at which the propellant is ignitable by surface contact therebetween;
• obturation means effective in the firing position between the barrel means and the ammunition holding means and between the air delivery means and the ammunition holding means;
• valve means associated with said air delivery means to close said firing chamber means relative to said source after delivery of the high temperature air to prevent flow of fluids from the firing chamber to the source after ignition of said propellant;
• movable breech means intermediate said air compression means and said barrel means;
• and
• means for separating said air compression means from said barrel means by axial movement between said air compression means and said barrel means, and by movement of said movable breech means intermediate said air compression means and said barrel means.

A device for firing a projectile from a firing position comprising:

• a barrel for guiding the projectile from the device,
• firing means operatively associated with the projectile in the firing position and being operative to fire the projectile through the barrel and being mounted in spaced relationship to the barrel,
• said firing means comprising an air cylinder and a firing chamber and an air flow passage connecting said cylinder to said firing chamber,
• one of said barrel and said firing means being axially movable relative to the other between a firing position and a loading position,
• a separate movable connecting member mounted between and in line with said barrel and said firing means and connecting said barrel to said firing means in the firing position,
• and means for moving said member transversely between the firing position in line with said barrel and a loading position spaced outwardly therefrom.

A firearm having an air ignition system for firing a projectile having an associated propellant capable of being ignited by surface contact with high temperature air comprising:

• barrel means for guiding the projectile from within the firearm after ignition of the propellant;
• ammunition holding means within the firearm for holding the projectile in a firing position within the firearm;
• air compression cylinder means providing a source of high temperature air by which the propellant is ignitable by surface contact therewith;
• mounting means supporting said compression cylinder means for axial movement relative to said barrel means between a loading position and a firing position;
• firing chamber means to which the high temperature air is delivered from said source;
• mating plug means and cavity means located between said compression cylinder means and said barrel means and being relatively movable between a firing position and a loading position as said compression cylinder means moves between the loading position and the firing position,
• said plug means and cavity means being cooperable with said ammunition holding means in the firing position to define said firing chamber means and surrounding said propellant;
• an air passage opening into said firing chamber means and being connected to said air compression cylinder means to deliver the high temperature air;
• valve means associated with said air passage and being movable between an open position permitting flow of high temperature air to said firing chamber means from said source and a closed position preventing flow of high temperature propellant gases from said firing chamber means to said source after ignition of said propellant;
• and
• an obturation means cooperable with said plug means in the firing position to confine propellant gases to said firing chamber means.