16inch AR: I am shooting 150 fmj at 2005 fps with 17.2 LilGun and a Federal Small Rifle primer. Note Fiocchi primers with the same load gives 1954fps. 17.2 LilGun seems like a max load but Speer Data goes all the way to 20.0.
Generally: the 300Blk is not a naturally accurate cartridge—500yards is a big reach for it.
I know, but it’s what I’m playing with right now. It’s just playing and saying I’ve done it.