300 blackout short stroking subsonic ammo

[Suputin]

I got away with titanium coated drill bits and a cheap HSS 1/8" end mill for the final cut. I sprayed high temperature paint on the untreated hole with a foam earplug in the bore, in the hope rather than the belief that it would protect the steel.
That post was 3 weeks ago, ARs aren't built in a day apparently.

I'm sure the paint will last once burning hot plasma is forced through the gas port.