I got into the 300 ACC round last summer. The reasoning was simple, I wanted an AR platform firing a harder-hitting round (than 5.56) from a short barrel/pistol. My discussion is for semi-auto AR guys who have either experience or decent knowledge about this round. If you don't like this round, good for ya, please move we don't need to hear from you
I am not YET a re-loader, but this round will likely turn me into one. It's expensive ($0.60/round and up) AND the ammo manufacturing community is still figuring out how to configure this round.
One of the great benefits of 300 ACC is it's versatility. You can shoot sub-sonic suppressed (not my thing) or supersonic (my thing). Because it is a 30 caliber round, there are MANY bullets to choose from and that's where I think the problem starts: this is a 7.62 x 35 round. But when one inserts a 147 grain projectile on a 35mm case length, then shoots it out of a short barrel, you do not end up with the ultimate in bullet stability. That's my experience
For purposes of HD/SD and hunting, I have found this hard to beat from Barnes: ($34/20. Certainly not for target practice)
2300+ fps (2100 fps from 8.5" barrel) 4-petal expansion up to .667 diameter. Very accurate and very terminal.
I think 110 grains - 125 is probably the 'wheel house' for supersonic commercial ammo. Remington recently introduced a 'target' round in 125 grains. I have been shooting a lot of Fionchi 147 grain and have seen 'key holes' at 200 yards, which is not acceptable. So sticking with the lighter stuff such as Sig Sauer ($25/20) or the Remington ($25/20).
Still to try: Amscor 300 acc supersonic, I've seen it for $12.50/20
I've had zero issues with cycling from any of the rounds I have tried.
Let's hear your experiences, looking for commercial options out there and also interested in hearing from re-loaders