Went range, AR10 issues

[jkornbread]

Ok, so me n wifey went to Cordova Shooting Center today to kill some paper. Only the 2nd time she has ever fired a weapon, and all she wanted to shoot was her 1911. So we played on the handgun range for a while and moved over to the 100yrd range to play with the new rifles. Shot the Sig for a bit and broke out the new AR10. I only had 40rds for it so I just wanted to play with it and check it out.
First 20rds were a mix of Federal (LC headstamp) and PMC. Shot great. No issues. I had purchased a 20rd box of Federal XM80C 7.62x51mm 149gr at the range store when we paid for our range time. God I had problems with this. I had 1 jam, damaging the case and the bullet was cocked in the case and several fail to feed...... WTH? Pulled mag, looked at ammo, no damage, made sure rounds are set right. First shot would fire next shot click........
after 3 or 4 of these the rest of the mag shot fine. Didn't shoot the other 9 rds in the box (I gave the guy in the lane next to me a rd to help him troubleshoot an ammo issue on his bolt rifle), too close to closing time.

This is a DPMS LR308 24" Stainless Bull Barrel

So, any thoughts?

[Knife Edge]

DPMS?

[rareair]

Not cycling properly. Maybe a dirty/blocked gas tube?

[jkornbread]

Not cycling properly. Maybe a dirty/blocked gas tube?

That thought has crossed my mind, its just weird to me that it started as soon as the I loaded the XM80C I started having issues. I will pull the gas tube tomorrow and see what it looks like.

[tiger222]

DPMS can suffer from bad bolt heads, my TAC20 had one, only ran on BH 168 until the change out from the factory. Then the BHO broke. Also the BCG should be DRIPPING in oil for the first 200 or so. I went and stayed with Armalite and now HK. The DPMS is long gone.

[Mr.1904]

Doesnt really sound like a gas issue.

[Dhena81]

So what kind of malfunction were you having? Is it ejecting spent brass and failing to feed? Or is it picking up the next round and not firing?


Edit:: For future reference an AR-10 is considered an Armalite main difference is they use a modified M1A magazine. A .308 AR that uses SR-25/DPMS magazines is generally considered a LR308

[jkornbread]

Ejecting and failed to pick up the next rd. Did it like 3 times. After it fed the rest of the mag range was closing so I didnt get a chance to run another mag through it.

Thanks for the tip on nomenclature. Im new to the LR308 arena.....

[Jakeisch]

Does it have an adjustable gas block?

[Knife Edge]

Either the gas key is loose, the gas block is crooked covering the ports and/or the rifle length buffer spring is binding in the tube. Larue makes a spacer that will allow you to run a carbine length spring assembly inside the extension. Had these problems with my early release OBR.

http://www.laruetactical.com/762-adapter-kit

http://www.laruetactical.com/super-duty-chrome-silicon-buffer-spring

[jkornbread]

No adjustable gas block. Gas key does not appear to be loose and looks to be well staked. I still need to pull the gas tube and check it but have been super busy.