A practice round as far as shotguns go, but still a serious amount of punch. With the idea of a shotgun from a staple gun on a roll, [Clint] continued the build by adding several more barrels ...

and the H&K and M16A2 rifles. It is suitable for use in most weapons with a 1-in-7 barrel twist. The M855A1 has a copper-jacketed steel core, differing from the previous M855 round which has a ...