I realize it falls outside the scope of your original question, but have you considered an AR-15 shooting heavy bullets like the 75gr-77gr Mk262 clones?
I owned a shorty AR-10 once, and will never go back down that road again. I wanted the AR-10 to work - I wanted the ultimate do-all rifle, and I did my best to make the perfect package, but I finally just gave up. They're just...
awkward. They're heavy for their size, parts are more expensive and there's less options, they're harder to get running as smoothly and accurately as an AR-15, clearing malfunctions is twice as difficult with the longer charging handle and heavier buffer spring, with shorter barrels the muzzle blast can be significant, follow-up shots are slower, etc.
A small/light AR-15 is sooo much more convenient. Parts are cheap and easy to come by, follow up shots are fast, loaded mags are lighter, they're reliable and easy to run, modern quality builds are pretty dang accurate right out of the box, etc etc
I know guys have been handloading the heavier .223/5.56 ammo for a long time, but in the past few years there has been more and more factory ammo being loaded with 75gr-77gr ammo and in my opinion it's a fantastic combo. Long range accuracy from short barreled AR's is easier than ever, and the terminal ballistics are nothing to be scoffed at.
Just something different to consider
