>>63951926
3d printing would never be useful in such a scenario. You can make a better gun with hand files, which you would already have in the low tech machine shop where you made your barrels. Hell, a slam fire shotgun made from 2 lengths of pipe and a nail would be better. Even ye olde handgonne + a lighter would probably be better.

Unless you think 3d printing a lower magically autocompletes the rest of the gun and adds 500 rounds to your inventory.