Gunsmithing Can a DPMS LR308 Headspace be adjusted?

[Ratbert]

I've got my first DPMS LR-308 with a factory barrel (the 18" fluted one) and it seems to have a VERY small chamber. The lands are right @ +/- 0.000 according to my RCBS mic and I have to push the shoulders on fired brass back to -0.004 or I have problems ejecting the round.

Given the magazine limitations the location of the lands is not much of a problem for me (though after seeing so many deep-throated 700's it surprised me from a factory gun) but I was wondering if there was anything I could ask a smith to do that would open up the headspace 0.003 or so. All my other guns are +0.002 or so and I'd really rather not have to resize all my brass to -0.004 just to make it run in all guns.

 

[Pat M]

Re: Can a DPMS LR308 Headspace be adjusted?

I have to use Forester Match dies for reloading mine, mine was a lot tighter than my PSS. Will yours run factory and surplus ammo?

 

[Kogapsp]

Re: Can a DPMS LR308 Headspace be adjusted?

Use a small base sizing die and you will solve your problem.

I only use small base dies on my auto loaders.

 

[Ratbert]

Re: Can a DPMS LR308 Headspace be adjusted?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Pat M</div><div class="ubbcode-body">I have to use Forester Match dies for reloading mine, mine was a lot tighter than my PSS. Will yours run factory and surplus ammo?</div></div>

I haven't tried it yet. It will load virgin Lapua brass ok.

 

[Ratbert]

Re: Can a DPMS LR308 Headspace be adjusted?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Koganinja</div><div class="ubbcode-body">Use a small base sizing die and you will solve your problem.

I only use small base dies on my auto loaders.</div></div>

Possibly, but just giving the normal redding body die an extra 0.002" turn seems to fix the problem. I was just wondering if there was any way to solve the problem without having to crank the brass down that far. If I have to, fine, I guess I'll just have to keep my current stockpile of a few hundred loaded rounds seperate from what I've loaded new for the DPMS until I've managed to shoot my way through it.

 

[wnroscoe]

Re: Can a DPMS LR308 Headspace be adjusted?

Since all chambers are cut and headspaced differently you really should have a set of dies for each rifle/caliber unless the same smith built the rifles using the same reamer and headspace gauge.

SB for gas guns, problem solved

 

[Ratbert]

Re: Can a DPMS LR308 Headspace be adjusted?

Well, this is a factory barrel but otherwise I see your point.

Could a smith conceivably run a new chamber in this and push it just the very smallest of fractions? Say, one revolution on the threads? I don't know how much room, if any, a gas gun barrel gives you for such things.

 

[wnroscoe]

Re: Can a DPMS LR308 Headspace be adjusted?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ratbert</div><div class="ubbcode-body">Well, this is a factory barrel but otherwise I see your point.

Could a smith conceivably run a new chamber in this and push it just the very smallest of fractions? Say, one revolution on the threads? I don't know how much room, if any, a gas gun barrel gives you for such things.

</div></div>

Depends on the headspace thats in the chamber now. A steel gauge would be the only way to determine that. If it's plus .001" or more, that'd be a bad idea.

 

[Outsydlooknin75]

Re: Can a DPMS LR308 Headspace be adjusted?

Old trick with AR style bolts and headspace ....... swap bolts around. One bolt may give just a hair more, some might give a hair less .... no telling until you do it and measure the headspace.

 

[DRAM40A1]

Re: Can a DPMS LR308 Headspace be adjusted?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Outsydlooknin75</div><div class="ubbcode-body">Old trick with AR style bolts and head space ....... swap bolts around. One bolt may give just a hair more, some might give a hair less .... no telling until you do it and measure the head space.

</div></div>

So, how many 308 AR bolts do you have lying around to switch and swap?

 

[Outsydlooknin75]

Re: Can a DPMS LR308 Headspace be adjusted?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DRAM40A1</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Outsydlooknin75</div><div class="ubbcode-body">Old trick with AR style bolts and head space ....... swap bolts around. One bolt may give just a hair more, some might give a hair less .... no telling until you do it and measure the head space.

</div></div>

So, how many 308 AR bolts do you have lying around to switch and swap? </div></div>

I dont ... but it is one option. As far as 223 bolts I have 2 or 3 kicking around.

 

[Hellbender]

Re: Can a DPMS LR308 Headspace be adjusted?

You can lap the bolt lugs and possibly increase HS a couple of thousandths, most AR bolts only have a couple of lugs touching until they really get broken in anyway.

Get some 600 grit Aluminum Oxide lapping compound from Brownells, a fired case and a good coated cleaning rod.

Remove the extractor and ejector from the bolt, degrease the bolt locking lugs and the BBL extension.

Put the compound on the lugs, put a fired case in the chamber and slide the cleaning rod down the BBL.

While applying pressure on the rod (against the wall....or if you have a small spring the right weight that will fit on the end of the cleaning rod to keep pressure on the case it works better) work the charging handle in and out slightly about 50 times, remove the bolt and look at the lugs, see if you are getting close to full contact, repeat until you are getting full contact on at least 5-6 of the lugs.

HTH

 

[Wild_Bill]

Re: Can a DPMS LR308 Headspace be adjusted?

I would use the small base die if you have excessive headspace by lapping the lugs more or by setting the shoulder back more on the cases you WILl end up with case seperations and have a lot of troubles with cases stuck in the chamber. the barrel has a tighter match chamber than most mil spec barrels so load to it. by just keeping bumping the shoulder back to get the rifle to function you do reduce the base of the case slightly but also create a major issue with seperations. buy a Redding small base full length sizing die and set it up to give -.001 thou if the fired cases are reading 000. this should solve your problems and give you the best accuracy you will be able to obtain also having 3-4 thou headspace clearence on the cases is not good for accuracy. like all match chambers if set to 000 that is the best you can aim for their is no way i would be adjusting it you could have the chamber run in further or the lugs paooed to give you more headspace or a larger diameter reamer run into the cham,ber to give you more clearence for the cases but you may as well throw the rifle in the bin as if you modify it their will be no comeback on DPMS if you start to have every seccond case seperate and get stuck in the chamber.

 

[Ratbert]

Re: Can a DPMS LR308 Headspace be adjusted?

I went ahead and ordered the small-base redding body die to add to my collection.

 

[Rovieairto]

Re: Can a DPMS LR308 Headspace be adjusted?

If you know that your chamber is at minimum you could buy a chamber reamer and increase your headspace that way.
A smith should be able to do this for you for less than the cost of the reamer.
Make sure that it really is out of spec beforehand.
DPMS chambers have a history of being tight in their .223 chambered guns.
Maybe this extends to the .308?
measure twice, cut once.