I only go by 5.56 data since I have no way to measure pressure myself and there's been some speculation on how the gov tests theirs, I just look for pressure signs and velocity. 2740 with a 77 SMK in a 16" barrel is hotter than I've seen. In fact it's close to MK262 in an 18" barrel. Fast barrels do exist but I'm gonna have to try AA2520 for myself.
