Originally Posted By SilentType:
Forget about 6.8 SPC.
I want an ACR barrel that is for the AAC 300 blackout. What a beautiful round that is from everything I've read on it just seems like total WIN.
If I were Cerberus I would go with an AAC 300 Blackout Remington ACR for the replacement of the M4 for that big leap the U.S. Army claims to be looking for since the round and the platform definitely take things up a notch.
Out of an 8" barrel, yeah, .300BLK has it going on.
Out of a 14.5" or 16" barrel, 6.8SPC significantly outpaces .300BLK.
Here are a few examples out of 16" barrels, all zeroed at 50 yards:
Track 1: .300BLK 123gr Remington supersonic factory load | from 300 AAC Blackout Web site
Track 2: 6.8SPC 110gr BTHP Hornady factory load | my chrono results
Track 3: 5.56 75gr Hornady TAP factory load (for comparison) | Molon's chrono results
IMHO .300BLK is great for shorter ranges, but for anything past 250 yards I'd definitely prefer 6.8SPC. The huge draw for .300BLK, of course, is that you just need a different barrel, vs. a new barrel, bolt, and magazines for 6.8SPC. I may eventually get a .300BLK upper, as I have an AAC 762-SDN-6 can coming, but it will not replace my 6.8 gun.