dpms lr 308 brass issues

[matthias]

hello all i have been searching the site and my search fu is not working. i have a real problem with my dpms lr-308 24 inch barrel 1-10 twist stainless.


specs on the gun- only thing changed is the trigger for an adjustable jp precision. everything else is bone stock

the damn thing is tearing my brass up really bad. it is removing primers from the pockets from three or four out of ten and creating a burr on the case head that looks like raised and ripped ejector marks. i have seen the ejector marks on other guns with hotter reloads this is happening with factory ammunition.

the ammunition is federal gold medal 168 gr
and buffalo bore sniper 175 gr sierras
all factory new

i have had the gun since 2002 or 2003 and have just started shooting it. accuracy is good. 15 three shot groups averaged to .65 inch center to center. but it does me no good if the primers are falling out and the brass is one time use.

how do i fix this? thanks for your help

 

[fastex500]

Re: dpms lr 308 brass issues

It seems like the DPMS 308 AR's have an issue being over gassed and/or too light a buffer:

http://www.ak47.net/forums/t_3_121/561330_.html

Primer issues may be due to bolt beginning recoil motion towards the back before the bullet is out of the chamber, causing pressure to push the primer out because the bolt isn't locked against the back of the case.

May also need an extractor upgrade:

http://www.ar15tactical.net/ar15_extractors.htm

http://762ar.com/dpms-lr-308-precision-rifle/

 

[smschulz]

Re: dpms lr 308 brass issues

I have a similar problem with Black Hills Match and Nosler Match in my DPMS MA TEN build.
FWIW ~ FGMM shoots fantastic in my rig.

 

[FCS]

Re: dpms lr 308 brass issues

Heavy up the buffer and modify gas block to reduce amount of gas cycling BCG/buy an adjustable gas block.

 

[matthias]

Re: dpms lr 308 brass issues

thanks guys i will do some modifications and let you know how it turns out.

 

[problemchild]

Re: dpms lr 308 brass issues

I smoothed out both my gas guns by installing the CS flatwire buffer spring (+20% pressure at rest). It keeps an extra 20% spring pressure on a closed bolt but has almost normal pressure when running back and forth. Its worth the 20 bucks. Both my DI guns land the brass in neat little piles now. No extractor marks and no brass denting. Also gets rid of any twoing sound from the buffer tube.