Re: subsonic .223
Here's my results using trailboss in a 1:7 12" barrel
62gn FMJ, OAL 57.4mm
6gn supersonic
5.4gn 50% subsonic - could be because powder measured electronically
5gn subsonic
55gn FMJ, OAL 57.4mm
5gn supersonic
4.4gn subsonic.
I'm about to try 5.2gn and a 62gn head next...