Powder choices, AA1680 for sub sonic, H-110 or WW296 for super sonic.
Bullet choices, 208 A Max for subs. 110 V Max, 110 Varmageddon, 125 BT, 125 MK, 145 tracer, for supers. Most any 30 cal bullet will function in my 300 BLK.
I have a 16" CMMG barrel with carbine gas. I mostly run with a Gemtech HVT suppressor.
I use Wolf small rifle primers and reformed mil 5.56 brass.
Of my several AR -15's it is one of the most fun to shoot.
This link will give you a ton of load data:
http://www.300blktalk.com/forum/viewtopic.php?f=141&t=86656