what is the most effective terminal performer out of a 10 inch ar15 barrel...762x39, 308, 300 black, something else? parameters are 0 to 150 yards...preferably 20 or 30 round mags. looking for foot pounds maybe
300 shoots out of a short barrel. A 110 Barnes does about 2000 out of a 9" barrel. A 115 10mm does about 1900. A 220 gr subsonic 300 is around 900 fps out of a 9".... A 45acp does that out a 1911.300bo is basically a pistol round, and does quite well out of a short barrel. now that their are plenty of bullets that will expand at lower speeds, 300bo is probably the reining AR 15 pistol champ. I would guess the 6.8 would top it's KE, but I think the 300 will perform better. 500 beowulf is actually a stretched 50ae, so that is going ton be the best one if you want to go thumper. 450 bushy is probably quite similar to 460sw, but haven't looked into it.
Why mention shotguns? The OP is wanting to build an AR-15 (pistol or SBR).But we haven't even mentioned shotguns....
Cause if we are talking punch at shorter ranges, it has it. Point being, what is a good weapon at short ranges... Well, SG isn't an AR, but it does have something to offer.Why mention shotguns? The OP is wanting to build an AR-15 (pistol or SBR).
I DO like your idea of a PCC for this purpose. Make it a .45 ACP or 10mm and you shouldn't get NEARLY the blast that you would get with a rifle round and still get adequate performance at the 150 yard and shorter range. Unfortunately, I don't now the numbers for ft/lbs energy at those distances. It seems like the OP is looking for high energy transfer at relatively short distances with standard capacity for ARs.
mtnlvr, I thought about the 6.5 Grendel, but with a short barrel and relatively short distance the Grendel is just not intended for this purpose. The starting FPS isn't there and the BC capabilities of the 6.5 projectile that retains energy at longer ranges are wasted.
Umm. Just to name a fewWhy mention shotguns? The OP is wanting to build an AR-15 (pistol or SBR).
The .30 cal rifle bullet has a very different ballistic coefficient compared to .40 cal bullet though.300 shoots out of a short barrel. A 110 Barnes does about 2000 out of a 9" barrel. A 115 10mm does about 1900. A 220 gr subsonic 300 is around 900 fps out of a 9".... A 45acp does that out a 1911.
It's not that any of that is bad... But shooting that round out of a short barrel turns it into pistol cartridge territory which... Why bother? With a rifle round, a short barrel still give more blast and flash for same ballistics... Where as using pistol cartridges in longer barrel doesn't. So why neuter rifle rounds, that are more expensive to achieve performance similar to pistol rounds?
The real plus is rifle rounds. A 14" carbine is well 5" longer.
Now there is a lot I could be missing. Have not looked much at true SBRs. But we haven't even mentioned shotguns....