BA 12.3 5.56 with gas block $100
https://www.weaponoutfitters.com/ballistic-advantage-performance-hanson-profile-5-56-barrel-w-750-in-gas-block.html...
My submitted 2 manual Form 1 applications and "rolled my own" using the Amazon kit. The only issue I had was that I didn't date block 9 and they sent...