A good trigger and good ammo are the first things to look at. I'd work on getting a hand load worked up that is as accurate as possible before considering anything else.
Quoted:
I remember seeing a kit for truing up a AR upper receiver . You would think having the face square with the barrel extension and having a good fit between the barrel / upper would help.
You can get it from Brownells, rather inexpensively too-$35. It can't hurt to check the face being true-and sometimes either finish machining or anodizing gets it "not quite right."
Free float tube, handloads, barrel, and trigger. in that order
barrel, Ammo, Trigger, free float, good optic and mount
Well, that sounds like a concensus to me, as far as it goes.
Funny, no one mentioned the fit between upper and lower, or in the LPK. Slop is the enemy of accuracy in every gun I've ever owned incuding semi autos.. With a 2 piece gun it seems like a loose fit would mean that the hammer never falls on the firing pin consistenly, or that BCG tolerances could push a round into the chamber differently each time. Even the extractor fit can affect how the case is held as it goes into battery. Hammer weight, hammer retun spring weight, firing pin material, torque specs are all things I've had to take into consideration with other guns. I know they aren't AR's but once you go past the SHTF syndorme (that's why we all have our go to M4) and get to a paper puncher these things have to matter.
I would certainly not worry about the chamber until I'd gone through all the other options
No offense, but that makes no sense to me at all. If I am going to start by spec'ing out a barrel from Krieger or Wilson or whoever. I think I would want the most accurate chamber on the market. I am new to .AR's but I see dozens of caliber options available (some just for throwing lead and some for accuracy) and that all comes down to different chambers for different results.
This mythical "Accurate" rifle that we have been discussing is a long term project, not the 90 minute build that my M4 was. I appreciate the starting points, and they make good sense, but am still looking for even the little "tweaks" that can make a difference downrange.
Has anyone experimented with any of this?