Pneumatic speargun without piston

Finished!

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If I read this correctly then the spear has two retaining mechanisms, a spear tail plug is held by the trigger mechanism in the rear handle and there is another release between the shaft and the spear tail plug that seals at the muzzle when the weapon is discharged. The second release lets go when the spear tail plug telescopes/compresses on impact freeing up some jaws which hang onto the rear end of the shaft which will actually exit the gun. Reliability of this system in actual use?

Just reiterating the purpose of this thread is to create a pistonless gun design that does not have a shaft retention notch at the front end of the spear. The above design meets this criteria (or criterion to be exact).

Absolutely True! Harpoon for the plug, plug for the valve! Time will show reliability!