LR 308 DPMS,, Extractor

[M ammo]

LR 308 DPMS,, Extractor

I have had this gun for a while, it has always been trouble.

Anyhow, it does not like to extract the spent case,

Yes I have changed to a heavy duty extractor Spring, and I have the little plastic thing in it, too.

My question out in Enos land,,, is their such a thing as an Enhanced

Extractor for a DMPS 308,, Bolt.?????????????

I’m figure if I replace the extractor I might as well go with the best one I can find.

[Dan Sierpina]

Not familiar with that, Jim.

I ordered one of these.

http://www.midwayusa.com/product/467621/dpms-bolt-component-kit-lr-308

All the bolt parts for a little more than just an extractor.

[fueddy]

How sure are you that its the bolt? I've seen a few DMPS 308's come from the factory with unfinished chambers so the rds wouldn't extract.

Just a thought

[co-exprs]

Not familiar with that, Jim.

I ordered one of these.

http://www.midwayusa.com/product/467621/dpms-bolt-component-kit-lr-308

All the bolt parts for a little more than just an extractor.

Hmmm, I got the same kit but mine didn't come with the little inner extractor spring as in the photo at your link. I went ahead and ordered an additional dual spring from DPMS, but there was a limit of one. My LRP-07 was dropping dueces on Sat. I tore it apart at home to find a broken extractor spring. Mine didn't come with a dual spring from JP, so I hope the replacement single spring gets the job done, otherwise I could be in trouble at Noveske this weekend. Gonna try the oring trick, but I don't have much time to mess with new stuff and unknowns. Don't much like being in this possition 4 days before a big match.

[M ammo]

I ordered that kit and the spring with the rubber ring and all that too,,

I changed out the barrel, to Rainier, so that should not be a problem,,,

hoping for the best,,

thanks for the input,

[carbon9]

I went through a similar problem with one of my home brewed DPMS pattern .308s with a severely over-gassed Rainier/Black Hole barrel. I did every extractor upgrade I could and I would still get stove pipes, double feeds or failures to extract. Sometimes the empty case would just be sitting on top of the empty mag. I tried a JP and Young MFG carrier. I tried heavier buffer springs, I tuned the gas. Yes, it would lock back on an empty mag. I did everything else I could think of, nothing worked. Although, every time I added a little bit of weight somewhere it ran a little bit better. Dave at Sun Devil MFG and Clint at heavybuffers.com both said the same thing, try a heavier buffer. So I went from a carbine stock and DPMS .308 carbine buffer to a rifle stock and rifle weight buffer and it was an instant cure. I managed to get 25(all I could spare at the time) consecutive shots out of it with no problems the night before SMM3G and it ran without a single hitch the whole match. I really wish I could have had more time with it I could be wrong but I think the combo of an effective comp, lighter buffer and light(125gr) but fast bullet was making it run almost as if it were suppressed. I still haven't tried heavier bullets 147gr and up yet, they very well could have solved the problem, i just don't know....yet.

As far as the extractor..... I haven't had time to revisit it yet since I put in the heavier buffer. I ended up with a single spring with the polymer insert inside of it and two o-rings around the spring. I did try just the double springs but it was at a time before the heavier buffer when nothing was working, including my current configuration. I don't think I need that much stuff in there but it is running very well at the moment. This is a JP enhanced bolt with a DPMS extractor, part of the process of elimination. I did polish the extractor, ejector and rounded the back edge of the bottom two lugs.

Good luck keep us posted.

[M ammo]

I have a full size stock on it,, but don't think I have a heavy,,, or know if the buffer is a 308 type/// weight,, I ordered new buffer and spring just in case,, if i need ot make the buffle heavy,,, I can add some weight,, I'll give it a try,, at this point,,, I will not have much I have not tried,, oh ya,, I'm shooting 147's- 150's

[carbon9]

.308 rifle buffers are just a touch shorter then AR-15 rifle buffers, with the extra length of an AR-15 rifle buffer the carrier wouldn't be able to come all the way back. 308 rifle buffers only come in one weight as far as I know unless you get one of the heavybuffers.com ones. I forgot, I also put in an Armalite buffer spring with the rifle buffer. Adjustable gas block? My Rainier Barrel gas port was huge, visibly much larger then the Criterion barrel I have. The problems I was having were even worse before I tuned my gas down. Almost as if the carrier was cycling way too fast and being forced back before the case could contract enough after the the initial expansion to extract properly. YMMV, this is just stuff I recently went through to get this rifle going, yours could be something as simple as your gas key isn't tightened all the way...... I'm just hoping some of this helps. I was starting to become frustrated enough to scrap the whole thing, I could never sell something that didn't run properly, thought I was gonna have to just shelve it or sell it part by part.

[co-exprs]

Problem solved. Installed a new spring with one of the rubber plungers inside and a single oring. I could barely squeeze it down tight enough to put in the pin. Took every ounce of grip strength, but I didn't have to result to any tools. I put 50rds through it this evening and it ran great with consistent ejection about 10ft at 2oclock.

[carbon9]

Problem solved. Installed a new spring with one of the rubber plungers inside and a single oring. I could barely squeeze it down tight enough to put in the pin. Took every ounce of grip strength, but I didn't have to result to any tools. I put 50rds through it this evening and it ran great with consistent ejection about 10ft at 2oclock.

Nice, those o-rings take some compression strength, no doubt about it. Should be a bit of relief, especially before a big match.

[co-exprs]

Yeah, I feel better. Still asked a buddy to throw his M1a in the truck as a back up, just for my peace of mind.

[M ammo]

I was going to shoot this gun for the exas Multi gun match,,, but its just not working,, I hope it is running by RM3G time,,, it has to be 99% or I'm just not going to put myself through IT again,, 3 gun is hard enough with guns that work,,

[co-exprs]

I've been thinking about your extraction problem. Mostly while I was on the toilet this morning...

Assuming good ammo, start with the basics and work your way out. You've implied that the problem existed before the barrel swap and you've got as much extractor tension as you can provide. So... if this is true then lets focus on other things. Begin by checking the head space. Either buy gauges or take it to a smith. It's quick and easy and won't cost much. If the bolt isn't right you could experience a barrel/bolt/extractor/case relationship which doesn't lock the extractor around the case correctly when in battery. Next check the extractor really closely. Look at the shape of the groove and make sure it is nice and square with a nice sharp hook. If there is any question at all, replace the extractor. Again... cheap and easy. Check to see if the case fits into the cup on the bolt face, without excessive slop. I don't know the specs for tbe cup but you should be able to stick a case in and make a high altitude decision as to the fit. Basically, there has to be a reason why the extractor is letting go. Either it's slipping off the case, or it was never engaged with the case at all. If the bolt locks on an empty mag, then there is plenty of gas. Too much gas can cause the extractor to bounce, but only at extreme levels and with weak extractor tension. So with the limited information I have, my gut tells me there is something going on with the bolt and how everything locks up. My buddies LMT is heavily gassed and he runs a suppressor. His rifle came with only the single spring with no orings or inner rubber piece. His rifle thumps pretty hard and throws brass half a mile meaning very possitive extraction. Changing up buffer weights to fine tune things is alright, but doing so to compensate for a problem doesn't solve the problem. In fact, it only serves to add another layer of complexity to the solution.

There's some limited perspective to consider. Or maybe I'm all wet. Either way let us know how it turns out. I'm curious about the solution.

Edited April 2, 2013 by co-exprs

[M ammo]

CO-exprs thanks for your input,,, I'm taking it all in,,, and ready to try,,, lots of things,,

at this moment,, this is hwat I'm going to do,, parts are on order,,

No Mil Surp,,, New factory or handloads,, nothing hot,, med, all small base sized,, they fall in and out of the JP chamber gage,,

I have not polished up the chamber on the new barrel,, but I'll give it a try,

My Plan at this point, is to polish, change to a new extractor, use the super duper extractor spring with the rubber donut,, change out to a new 308 buffer and new 308 buffer spring,, and see what happens,,,

the only other things I could think to do,,, is play with the weight in the buffer, make it heavy,,, or lighter,,,, and get an adjustable,, gas block.

Thank you!!!

[co-exprs]

I've read where some seem to think that the 223 and 308 extractor springs are the same, while others say they are different. I scoured the internet for 308 extractor spring options and really only found 2. A standard 308 single spring and the DPMS double spring. I took apart a JP 223 bolt, a milspec LMT bolt and my JP 308 bolt. Both 223 bolts had the little rubber piece, while the 308 bolt did not and both of the 223 springs looked the same (about 4 coils and the bottom coil flared a little). The 308 spring had 5 coils, visibly thicker wire and had noticably more tension to compress. Both springs were the same OD with the 308 spring being a slightly tighter ID (due to wire thickness). The little rubber piece fit into the 308 spring, but it had to be massaged into place as the 308 spring was not flared on one end. I've ordered a DPMS dual spring and will give that a try as soon as it gets here. I've not personally seen a 308 specific spring kit with an oring and rubber plunger. If that is what you ordered, then make sure you got a powerfull enough spring for 308.

Just for the record, my LRP-07 ran perfect on just the single 308 extractor spring for about 1000rds before the spring broke. My reason for trying the oring and rubber peice was to take some of the force off the spring to make it last a bit longer. I was more worried about it not running at all with the additional parts installed than I was with tension. I tried to contact JP, but they are so busy they haven't replied yet and I had to get something together befor the match this weekend.

[Mark Gale]

I've been thinking about your extraction problem. Mostly while I was on the toilet this morning...

Assuming good ammo, start with the basics and work your way out. You've implied that the problem existed before the barrel swap and you've got as much extractor tension as you can provide. So... if this is true then lets focus on other things. Begin by checking the head space. Either buy gauges or take it to a smith. It's quick and easy and won't cost much. If the bolt isn't right you could experience a barrel/bolt/extractor/case relationship which doesn't lock the extractor around the case correctly when in battery. Next check the extractor really closely. Look at the shape of the groove and make sure it is nice and square with a nice sharp hook. If there is any question at all, replace the extractor. Again... cheap and easy. Check to see if the case fits into the cup on the bolt face, without excessive slop. I don't know the specs for tbe cup but you should be able to stick a case in and make a high altitude decision as to the fit. Basically, there has to be a reason why the extractor is letting go. Either it's slipping off the case, or it was never engaged with the case at all. If the bolt locks on an empty mag, then there is plenty of gas. Too much gas can cause the extractor to bounce, but only at extreme levels and with weak extractor tension. So with the limited information I have, my gut tells me there is something going on with the bolt and how everything locks up. My buddies LMT is heavily gassed and he runs a suppressor. His rifle came with only the single spring with no orings or inner rubber piece. His rifle thumps pretty hard and throws brass half a mile meaning very possitive extraction. Changing up buffer weights to fine tune things is alright, but doing so to compensate for a problem doesn't solve the problem. In fact, it only serves to add another layer of complexity to the solution.

There's some limited perspective to consider. Or maybe I'm all wet. Either way let us know how it turns out. I'm curious about the solution.

Interesting statement... Assembling your rifle with plumbing parts is a legit fix but a heavy buffer is nothing more than another potential problem.

[co-exprs]

I've been thinking about your extraction problem. Mostly while I was on the toilet this morning...

Assuming good ammo, start with the basics and work your way out. You've implied that the problem existed before the barrel swap and you've got as much extractor tension as you can provide. So... if this is true then lets focus on other things. Begin by checking the head space. Either buy gauges or take it to a smith. It's quick and easy and won't cost much. If the bolt isn't right you could experience a barrel/bolt/extractor/case relationship which doesn't lock the extractor around the case correctly when in battery. Next check the extractor really closely. Look at the shape of the groove and make sure it is nice and square with a nice sharp hook. If there is any question at all, replace the extractor. Again... cheap and easy. Check to see if the case fits into the cup on the bolt face, without excessive slop. I don't know the specs for tbe cup but you should be able to stick a case in and make a high altitude decision as to the fit. Basically, there has to be a reason why the extractor is letting go. Either it's slipping off the case, or it was never engaged with the case at all. If the bolt locks on an empty mag, then there is plenty of gas. Too much gas can cause the extractor to bounce, but only at extreme levels and with weak extractor tension. So with the limited information I have, my gut tells me there is something going on with the bolt and how everything locks up. My buddies LMT is heavily gassed and he runs a suppressor. His rifle came with only the single spring with no orings or inner rubber piece. His rifle thumps pretty hard and throws brass half a mile meaning very possitive extraction. Changing up buffer weights to fine tune things is alright, but doing so to compensate for a problem doesn't solve the problem. In fact, it only serves to add another layer of complexity to the solution.

There's some limited perspective to consider. Or maybe I'm all wet. Either way let us know how it turns out. I'm curious about the solution.

Interesting statement... Assembling your rifle with plumbing parts is a legit fix but a heavy buffer is nothing more than another potential problem.

LOL. Point taken. If you note, I also said that I have a DPMS double spring on order and that my rifle runs fine on the factory single spring. I didn't really have a problem to solve, only a spring to replace. With my rifle running properly I have room to experiment. Not discounting the use of heavy buffers, only that there is a root cause problem with his rifle which needs to be understood and solved. That's why I wrote heavy buffers for fine tuning. It's all good though. Nice jab to keep me awake.

When I was much younger, I used to play paintball a lot. I had this new marker that wasn't running quite right. I like to tinker, so I started buying aftermarket parts to make it run the way I thought it should. The marker just got worse and worse. I finally got smart and stripped off all the aftermarket parts and got it back to factory. Then I found the root cause problem was a bent vavle shaft. With that fixed, the marker ran exactly the way it was supposed to and I was very happy. After that lesson was learned, I always look for the root cause before swapping parts to mask the solution.

[Mark Gale]

"AR-10" pattern guns have always been problematic. While you will run into people who claim they have thousands of trouble free rounds through theirs, most will report extensive fonkey mucking over the life of ownership which amounts to less than a couple hundred rounds. The large frame race gun crowd is another story.The SR25 and a few custom builders appear to have solved most of the problems but their cost puts them out of reach of most users.

[M ammo]

If I spent my Money of a JP or a LaRue, I would have been better off,,,

[co-exprs]

If I spent my Money of a JP or a LaRue, I would have been better off,,,

Yes and no. Not sure what you have to do to get your hands on a Larue, but I'm going on a year back order with no movement on my order. I really enjoy shooting my LRP-07 and it's a tack driver, but there are some things about the side charge which I would like to see improved upon. Mark Gale is right. They all have thier little quirks. My buddy Rich built his own. The more I learn about the 308's the more I like his personal build.

[TheDude]

I've seen 308 bolts that the extractor spring is too long (specifically with the new single spring design) and will not slip over the case very well which will lead to FTE issues. Also because more stress is being put on the extractor itself they will break sooner then normal. If this is the problem you are having then by putting more tension on the extractor will not help. If you take bolt out of the rifle and push the extractor back with a punch, the extractor should clear the bolt face. If it doesn't then the spring is too long when fully compressed.

[M ammo]

well,,, I got the new buffer spring and new buffer. they are 308,,,,,,,,,,, so says the tag,,, now the buffer was the same as the one in the gun,, same weight too,,, the spring was different,, it was not a tightly wound, it had less coils per,, inch,,

more to come as parts come in,,

[M ammo]

as you can see the old one on the right new on the left,,, both DPMS,,, but not the same,,,

[M ammo]

oh ya,, I got the Donut thing,, put it in,, but the new,,, extractor spring,,, was not that strong,, I had a beefed up one that was thicker longer and stronger,, so I have a stronger extractor spring,, with the rubber insert, in it too.

I'll polish out the,, chamber tonight and test fire it this weekend,,,

[jobob]

I too have an LR308 and used to have mega problems. Installing a new extractor helped. Changing to the JP enhanced 308 bolt helped a LOT. And the final cure came from changing to Magpul magazines. Haven't had a malfunction for quite some time, not that I shoot it a lot, but I do consider it to be a reliable gun now.