I bought a 18" 6.8 barrel and can not get it to shoot as advertised. I have tried 95 gr ttsx 110 gr vmax and 120 gr sst. I have tried H322 and AA2200 doing optimum charge weight load development with each powder with each bullet. I played with seating depth from 2.260-2.295 in .005" increments. I have also used 2 scopes to rule out scope issues too. I took the muzzle break off and shot it without. I also looked at the crown using a magnifying glass. The gun is gassed right as the brass is landing at 3-4 o'clock. I even bought some factory hornady ammo just to see what kind of difference it made and I was getting 3" groups using that. I have put close to 200 rounds through this barrel trying to get it to shoot something half way decent. The best group I got was 120 gr sst over 27.2 gr of 2200 with OAL of 2.285" and that was a little over 1.5" group. I shoot off sandbags to ensure the best rest I can. I have several other ar's not in 6.8 and all of them will shoot under MOA with a couple of them shooting 1/2 MOA. Also, trigger is a crisp 2lb trigger. I have been working with the manufacture with this issue and they are very helpful and easy to deal with, I'm just trying to figure out what it could be as I've built a bunch of ar's using several different barrel makers and have never had this hard of a time trying to get a barrel to shoot that was guaranteed match grade accuracy. As of right now I sent my complete upper to the manufacture for them to do some testing on it. Just curious if anybody else has had this problem and was it a bad barrel that needed replacing?