DPMS AR-10 with issues

filmjunkie4ever · Sep 21, 2016

Gentlemen -

First off I am COMPLETELY out of my league on this one. I have little to no experience with the AR platforms.

The rifle in question belongs to my brother in law. He bought it new in the box on Gunbroker.com this summer. The ammunition is Winchester Power Max bonded .308 150 grain factory loads.

Today at the range, he was attempting to sight in. His smallest groups were running 3"-4" and I would say a goodly 70% of the cases were either popping primers or showing cratered primers and other extreme pressure marks on the cases. Again these are factory loads, purchased mere weeks ago from the local hardware store. Due to the obvious danger, we retired from the range.

I have checked Winchesters website for any product recalls but have found none that would be related to this.

Is it the gun? Or is it the ammo?

Never once have I seen factory ammo pop or crater primers. Is the chamber throat too short? His cases don't appear to be stretched so I don't believe it to be a headspace issue.

Opinions?

Thanks -

Dale

Thebear_78 · Sep 21, 2016

Couple questions.

Is it a gen II? If so the are generally over gassed and an adjustable gas block will fix it.

When it ejects the brass are the flying a great distance and rim of the brass getting chewed up?

When they went to the gen II reciever they made the bolt much lighter, without the extra mass in the bolt the bolt will actually start to open before the bullet is out of the barrel. This tears up brass something fierce.

The cratered primers are from excess play between the bolt and firing pin. A call in to DPMS and they will replace the bolt. I ever bothered with replacing the bolt on mine, it's not a pressure sign it's common on many mausers with large firing pin holes too.

A web search on DPMS lr308 cratered primers will show the same.

http://www.brownells.com/rifle-parts/ga ... 67679.aspx

Sent from my iPhone using Tapatalk

filmjunkie4ever · Sep 21, 2016

Yes it is a Gen II.

He is calling DPMS tomorrow. Hopefully they take care of him, he is quite angry right now. Pay that much for a gun, you get the idea.

Thanks -

Dale

Thebear_78 · Sep 21, 2016

The newer one are supposed to be better.

It sucks but that gas block will fix the gassing issue. The cratered primer isn't a big deal since it's not pressure related.

The adjustable gas block will make a world of difference.

Mine was doing the same thing until I swapped out the gas block. $100 and 10 minute fix, better than DPMS will do for you. After the gas block swap I still had cratered primers but it shot and functioned very well with no more brass damage.

Sent from my iPhone using Tapatalk

filmjunkie4ever · Sep 23, 2016

So he called DPMS yesterday and it sounds like they are sending him a replacement gun once his is returned to the factory. They are going to pay for return shipment as well.

It wasn't the cratering as much as the blown (popped) primers that was giving us cause for alarm. Out of a box of 20, this happened 7 times with factory loads, so we knew something was amiss.

Sounds like they're going to take care of it, the new one should be here in 6-8 weeks time.

Will advise.

Thanks -

Dale