A popular platform for building DIY “zip guns” is the humble staple gun that is easily obtainable at your local office supply store. This is a four shot model (not sure if that means 4 shots fired all at once, or four barrels each fired on a single pull of the trigger, like the famous COP .357 Derringer). The reader who sent this in explained the name he gave it …

Yeah, another ubiquitous staple gun derivative. This version is a 4 shot .410 that sometimes masquerades as a caulking gun, hence the name, the Kaulkinator or K-441. Still untested with a full load. This has been designed for 2.5″ shell and slugs. An inertial pin on a heavy spring keeps things safe. It’s a little big, but for a first attempt at a DIY (non-3d print) firearm with only a small drill press to work with, I think it worked out well.

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