Not sure which forum section to put this in, but wanted to run something by the sigforum brain trust that is ammo related.

I have been making powerheads for spear fishing. They slip on the tip of the shaft and when they hit the fish the shaft impacts the primer.

The fish is killed instantly by the gas/shockwave.

So far I have been using 1/2” 316 stainless tubing with a 1/16” wall diameter to act as the barrel/chamber. The barrel has a .375 ID so the bullet is able to slide in until just before the extractor lip, once I swage the tube just a bit.

My question is, for my given purpose, basically a gas delivery system, is there really any value in having the shell casing nearly completely inserted in the barrel or would it likely be just as effective if the “barrel” only covered the projectile and say half way down the casing?

I won’t be reloading any of the bullets and the projectile hitting the fish isn’t a concern. This is purely a gas/shock delivery system.

I could just make one in a short configuration and try it out but the waters cold right now..

As a side note I originally made my powerheads on a 3d printer with the understanding that they would be disposable and would basically disintegrate when used, which they did. The problem I found was they were not as effective because the gas was not directed forward. Since then I began sleeving them with stainless tubing and they work as designed. Highly effective. Cheap steel tubing from HD works just as well but I don’t always use the powerheads on a dive and didn’t want them to turn into a ball of rust and leak/stain my gear or areas of the boat with rust.

Lastly, these are legal in Florida as long as you are in federal waters.