It's the velocity hence maximum range that I've not seen an AR make. See post #? by StarMetal with it's velocity chart. Looks correct to me. However with a non gas vented bolt gun in 26 barrel I've no trouble sending a 53gr bullet at over 3,400 fps. I've shot next to two different long barrel AR's prairie dog shooting. Even after swapping ammo the bolt gun had between fifty to one hundred yards range on the AR. Swapped shooters too. None of my bolt gun loads exceeded published data.
White Oaks sells 26 AR barrels with a gas port moved 2 forward but they do not advertise an increase in velocity. Port pressure with slow powder is supposed to be the reason for moving the port forward.
Arching heavy for caliber bullets at long range works better on paper than on an unknown range moving critter. 8 twist bolt guns with 69 grain bullets do not make hits on dogs at long range over a 50 grain Blitz-King from a 12 twist barrel. It's not even a contest. All those 600 yard scores you see AR match rifles turning in with 77 or 80 grain bullets don't mean much out in the field. For one thing they take to long to get there and the critter moves out of the way of your bullet. Note you do not see a big move by small varmint shooters into heavy for caliber bullets. Sierra 65 grain Game King is one heck of a yote killer though. Which is what my 20 AR is set up to shoot along with it's sister 69 grain MK.
I have three 22 rifles. A 5.56mm AR a 223 AR and a 223 Bolt gun. All are set up for completely different task and the ammo for them is not interchangeable to the point where most of it will not even chamber in another rifle. Bolt gun for instance gets neck sized cases that will not chamber in either AR. I do get to use the same high price match grade dies and all that prep equipment but the ammo must be labeled as to what rifle it shoots in. If I shoot cases sized to fit the 223 rifles in the old 5.56mm rifle groups open way up. You can have a 1 and a Ό inch rifle or a 2 1/2 shotgun. I've never checked to see what rounds interchange since it's a moot issue. That's what ammo cans with stickers are for.
I did purchase a 1,000 piece box of Hornady once fired cases for $50 dollars off reloadersauction dot com this winter. That right there is a reason to shoot 223 rilfes.
22 bullets are cheap and cast boollets can be made in a years suply from one pot of lead.
Never have set up on the 500 yard line at Effingham , Illinois with my 20" barrel AR with 69gr MK's against my Rem 700 26" with 50 grain blitz-Kings. Only run irons or a 1x X 3x Weaver on the AR while I have a 6 x 24X on my bolt gun. But the trigger pull alone would be a game breaker.