Pick up a bob sled so you can single load rounds in the chamber/lock the bolt down on the chambered rounds to first weed out if the problem is loading issue, or just a barrel/bolt issue.

If a feeding issue, then need to check the angle of attack out of the mag, up the feed lips, and them to make sure that the bolt is locking up the same way every time; either a first round cycle and when it live cycling as well.


If a barrel problem, then pull it to make sure its straight to start with, the chamber and bore is concentric to the side walls of the barrel,  and maybe even lead lap the rifle as well.  Also with the barrel off the rig, good time to not only polish the inside of the barrel extension lugs, but the bolt as well.
When the barrel is reinstalled, make sure that it free floating, the barrel nut is correctly tightened, and the gas tube is correctly indexed with the carrier key.


One last thing, and that you need to send a fouling shot down the barrel each time it's cleaned before starting your groups, and If you are allowing CLP to get into the chamber and bore, then it will take about 14 rounds until you blow the CLP/Teflon out of the bore so the barrel will settle in as well.  Hence if you are going to run a AR for tight groups, then you want to run it without using  much to any lube, much less CLP.

Yep, CLP is the stuff to keep the guns running for longer periods since it has a cleaner in it that does dissolve fouling before it gets a chance to build up, but counter productive on shooting tight groups since once it gets int the bore, take more than a few rounds to shoot it out; and only if you can keep it from continuing to get in the bore again as well.

To be blunt, clean the bore with Sweets to get it clean and dry, hit the rest of the rifle with something like Gun blaster to get those parts clean and dry, and then your going to break out the "secret lube" in trace amounts to just give the upper receiver bearing parts a hint of  very light lube to allow it run for the short shot strings that you would run in a match isntead.

On some rigs, although the Buffer should prevent bolt bounce (carrier bouncing back off the face of the barrel extension at loading), it can still happen, and if you have bind between the gas tube to the key as the carrier is trying to come back forward after the bounce, it can keep the bolt from totally cam'g over for a full lock up isntead.

This can cause a slight inconsistency in head spacing for that shot, as well as bolt unlock too, which can produce the flier.

You need to pull the barrel to first check to make sure that the barrel bore is straight, and then the install of the barrel next .

Hence a slightly bent barrel dead cold is going to throw the first round more towards it bend, and then as it gets heat  and the bullet down the barrel can pressure force the barrel a little bit straighter as it going down the barrel, the rest of the shots will be more in line with front/end line of the bore isntead.

Same goes for the barrel nut not being tight enough, or even the face of the barrel extension to the upper barrel socket not being a clean surface fit at as well.

Truth is, before I will install a barrel on a target type rig, will face the end of the barrel extension to get it on face with the center line of the receiver, then chuck the barrel up in a lathe to not only check to make sure the barrel is straight/the bore is concentric to the barrel walls, but face the  receiver extension if need to true it to the center line of the bore as well.  Also while I have the barrel in the lathe, can address any problem that the chamber entrance has that may not allow a clean feed into it as well (back edge of chamber too sharp/not enough edge radius on some barrels).