+1. Now I don't know "delusional" is the right word...INEXPERIENCED in comparison is perhaps a better. In reading many of the comments above, it is clear to me that some are trying to apply many of the same precise principles we Benchrest and precision/competition Shooter use in Bolt Gun reloading to AR's. That my friend AIN'T GONNA HAPPEN. Now I claim no spectacular expertise with AR's, but do know from experience, that it is a pipe dream to believe that any AR, custom or otherwise, will ever keep up with a Precision built bolt gun. And my experience comes from having had a custom built AR15 (San Tan Tactical Upper/Lower, PRS Stock, JP Precision Parts and Barrel) built by a master Gunsmith who competes and built my rifle to mirror his competition AR15. And though if I load each round by hand and play with seating depth, my 5 shot groups do tighten up a tad, though those 5 shots are all touching one another using 77 gr Sierra and are darn close using 69 grains when I load from a Magpul magazine, that at 100 yds. Now I admit, I am the weak link in the cycle because at 70, my eyesight isn't what it was when I was 30. But back then AR's weren't made like they are today, as I ended up giving a few to my boys as they could care less about 5 shots group touching, so long as the damn thing hits what they aim at. But I will add that no matter the AR make or model, you still have to test for both bullet weight and the powder it likes best. And that feature is no different than any of weapons for which someone would reload for.
But might I suggest, that as others have already said, don't set yourself for disappointment by expecting more out of a weapon than it is capable. From experience over several years, a $1500 AR is not going to shoot like a $3000 - $4000 AR. And the person pulling the trigger may well be the difference in even getting close. But of course, each of us has to be honest with their ability (inherent or learned) to hit exactly what they aim for. And that, my friends, is the toughest part of the equation to master. Having seen it time and time again where people complain about the weapon's inaccuracy, only to have someone whose an accomplished shooter, pick up the same rifle and shoot some fantastic scores or targets.
Lastly, do try the 69 and 77 gr Sierras. The powder that has worked very nicely for me is VVN140 in a JP Precision 1:8 chamber. Might consider also trying some VVN530 or VVN540. No guarantee your rifle will like them. But you won't know until you test some. Most importantly, have fun and good luck in your efforts. But don't waste your time chasing the impossible dream that only happens in trash talking or the movies.
Alex