I have been thinking about a new project gun, I was wondering if anyone has experimented with subsonic heavy 450bm in an ar15. I am wondering if you can get subs to cycle reliably. I was going to pick up a lee 405 or heavier to start with. seems like all barrels are 1 in 16 twist, carbine gas. And is carbine gas OK or should I get a custom pistol gas barrel like is preferred with 300blk.
I was just wondering what you guys have figured out to save me a little time and headache or if it is a waste of time.