Fluid pressure repeating pistol with unitary barrel and hammer assembly

A repeating pistol of the fluid pressure powered type comprising:

• a main frame including a handle portion;
• means defining a closed chamber fixedly mounted on said main frame and including means affording connection of said chamber to a source of fluid pressure, and having a normally closed valve at its forward end;
• a unitary assembly slidably mounted on said main frame including a barrel forwardly of and a hammer rearwardly of said chamber, said assembly being biased rearwardly and movable between a forward cocked position, a rearmost firing position and a fired or rest position just forward of the firing position;
• a trigger pivotally mounted on said frame and having a sear engageable with said assembly for releasably holding said assembly in forward cocked position;
• and sealing means carried by said valve and engageable by the rear of said barrel to establish sealed temporary fluid communication between said chamber and the rear of said barrel when said barrel moves from its cocked to its firing position;
• said hammer in its rest position extending rearwardly of said main frame and handle portion whereby a user may cock the pistol while holding it substantially in firing position by merely slapping the hammer with his other hand.