The threads on a stock MPX barrel have about 3 mm of thread and a taper for interfacing with Sig's proprietary taper mount system that is integral to the barrel. That way Sig firearms are most compatible with Sig muzzle devices, and vice versa. It's a shame, I'm having mine re-threaded. Thanks Sig.

Anyways, I couldn't wait to shoot it suppressed so I threw on my HK Parts 3-lug adapter which has almost an inch of exposed thread. There was a lot of thread left over in front of the muzzle. I knew it would get a bit dirty, but boy did I underestimate how tough it would be to clean.

This is a tap designed to clean out threads. If you print in metal it might work for actually creating new threads, but that is not what this is designed for. Also I take no credit for the 13.5 LH drawing, but that is what this was loosely modeled around.

I am mostly uploading this to illustrate a concept of bringing a reasonably accurate, custom designed, purpose built tool to production in your own home, but if you're in the same predicament I was, glad this can be of help!

FFCreat0r

No

No

100 micron or less

80-100%

If printed in PLA, be mindful of the quick heat generation of friction which will quickly degrade this tool's performance. Haven't tried in ABS. PLA seems to hold more of an edge so I started there.

I soaked in Hoppe's #9, went at it with a fresh 3D printed tap, burnt off the threads, then repeat the cycle until all the carbon was removed. I also had to use some wire brushes on a drill, and a small flathead screwdriver at the front end of this muzzle device, where the most crap had built up.

Works great with HK 3 Lug Knob!

http://www.thingiverse.com/thing:1733574