I just finished building an AR 10 from PSA upper and lower. I took it to the range this past weekend to break in the barrel and get it sighted in. I like to use Tubbs final finish ammo for break in. 20 rounds of this fed fine. Then I switch to Magtech CBC 147 gr fmj. From a 10 round Magpul magazine, the rounds would not fully chamber. They seem to but would not fire unless there was only 1 on the magazine. With multiple rounds in the magazine the round that chambered would fire if I pulled out the magazine and then pulled the bolt back and let it slide forward again. I did use a Tubbs flat wound buffer spring so i will try the standard spring with that ammo. They may be a bad combination. Has anyone else experienced this with that ammo? Also accuracy seemed poor. Do you have any recommendations for reasonably priced quality ammo for target shooting?