I'm going to stick with 6.8 in my ARs, but really considering building a lightweight 300 Ham'r on a M700 .378 action I have on hand. I bet a 20" #1 would be sweet for woods hunting whitetail and hogs locally. I notice you hardly hear the 125 NBT mentioned due to length, but I believe it will work fine in a bolt action. Curious why they haven't developed more loads with powders currently popular for the BO such as 300MP, LG, 296/h110 etc. You hardly ever see 1680 or CFE Black here.
Yes, the Nosler BT uses up some case volume because of the BT. The Sierra ProHunter and the 125gr TNT don't have that, so they leave more useful volume. And frankly, a BT isn't needed for this short range cartridge. It just doesn't help much at ranges under 250yds or so.
I ran the velocity numbers I got from NBT vs SPH and the NBT didn't catch up velocity-wise until past 200 yds.
I haven't tried 300MP or LG, but 266/H110 is too fast to operate a midlength gas AR with a .110" port. I think you need carbine or even pistol gas for those powders. I wish I could use those, but 1680 and CFE Blk, etc are pretty darn sweet so I don't complain too much.
