Magtech CBC 7.62 x 51 not seating

[stickflickin]

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?

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[Medic!]

PSA barrels are known to have problems with tight chambers.

Did you not research PSA?

 

[stickflickin]

I had not heard that. If that is the problem then why will it feed fine with one round in the magazine? I will try different ammo and buffer spring with ammo that wouldn't work

 

[stickflickin]

Also Tubb final finish ammo fed fine with multiple rounds in magazine

 

[stickflickin]

I checked chamber fit by dropping a round in. Doesn't seem tight. The round falls right out as it does on my RRA 5.56.

 

[R3dundantC]

Also accuracy seemed poor.

Might be your rifle. I've always had good results with CBC. These groups were shot with CBC 168gr HPBT at 105yrds

I had not heard that. If that is the problem then why will it feed fine with one round in the magazine? I will try different ammo and buffer spring with ammo that wouldn't work

Try a different mag?

 

[stickflickin]

That may be better grade CBC. This is mil surplus. Yes, need to try different mag.

 

[whiskeybill]

My brother has an Armalite AR-10 with a match grade barrel and has the same issues. Some mags feed flawlessly and others pull the same stunt you describe. The ammunition didn't seem to matter. The match chamber can be finicky as well. Shooting some LC match ammo one day, and one round would start into the chamber, but the bolt wouldn't lock up. I had to look real close at the suspect round, but found it to be slightly out of true axis (bent for lack of a more simple term). I told him to sell the magazines that were giving him problems and keep the functional ones. Incidentally, they were all Armalite magazines.

 

[stickflickin]

Went back to the range with different ammo, magazines and buffer spring. Different ammo and magazines still had feeding problems. Replaced David Tubbs flat wire buffer spring with the original one. Runs like a Swiss watch now. I like their final finish ammo but the AR pistol grip that I bought from them was made wrong and now this issue with the buffer spring doesn't impress me