Haha, glad you followed through with my idea, it looks awesome!
Why not try making one in a bit of a reversed configuration (this is how I had originally thought it would have been done)
Have the shrader where the narrow bit of the cartrige is (not sure of it's name, but the bit that holds the bullet. Not sure what cartrige would match a shraeder... Sadly I've never had a chance to fire a real gun
) You'd probably have to cut that part of the cartraige off, and replace it with the shreader.
Anyway, do that and have the barrel sitting where the primer would usually be (just have a hole, and have the barrel flush with the rear of the cartriage) This would make it look like a spent cartriage, although the front of it would be threaded. So you'd fill/pilot it from the end where the bullet used to be, and the projectile would leave from where the primer was.
What sort of noise does this thing make when it fires?
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