DPMS308 FEEDING PROBLEMS

mrmackc · December 9, 2014

I finally got the hang of being so concerned about problems on my fav forums...........You need to check the dates the discussion started and how it morphed to the present year, month, and week before going ballistic on some flaw that was fixed year before last.

darb · June 26, 2015

Just a bit of info for everyone else - there is no such animal as an "A2 receiver extension" - buffer tube, whatever the names are that come up. Real name is "Receiver Extension."
There is only an AR-15 Receiver Extension, when talking about the rifle-length tubes. It's the original, and the only - there isn't one that's longer, or A2 length. All the A2 is, is the A1 or "standard" rifle extension with a 5/8" spacer, and a 5/8" longer buttstock screw (hollow through the center).
So, in short, don't waste a metric poop-ton of time trying to search out a specific receiver extension that must be A2 length. You'll find a unicorn before you find that thing. Just hunt for, and easily find an A1 length, or "standard" rifle receiver extension, and you'll save some serious heartache.
The Magpul PRS, both AR-15 and .308 AR, use the A1 extension, for what it's worth.

What would happen if you had the prs, did not use the spacer and cut the buttstock screw 5/8'' shorter?

blue109 · June 27, 2015

PRS doesn't use the spacer. The spacer, when needed, goes on the rear of the extension. If you were using a stock that was A2 length, and left the spacer out...you would still need the long screw. It would just pass through empty space where the spacer would be until it threaded into the extension.

darb · June 27, 2015

PRS doesn't use the spacer. The spacer, when needed, goes on the rear of the extension. If you were using a stock that was A2 length, and left the spacer out...you would still need the long screw. It would just pass through empty space where the spacer would be until it threaded into the extension.

mmm My story with the PRS: With the long screw installed it would not allow the bolt carrier to come back far enough for the bolt catch to work properly and would not allow the bolt carrier to come back far enough to pick up the next round so I cut 5/8" off of the screw. The bolt carrier will latch properly now. I have not function tested to see if it will pick up the next round as of yet, but it should. thanks for the reply

98Z5V · June 27, 2015

^^^ Right. The instruction card that comes with the PRS specifically states to use the shorter screw - the stock even comes with it.

In basic, you tried to use the longer A2 screw in an A1 setup - the reason they tell you it won't work is because you'll slam the bumper on the buffer on the extended screw.

Edited June 27, 2015 by 98Z5V

darb · June 27, 2015

^^^ Right. The instruction card that comes with the PRS specifically states to use the shorter screw - the stock even comes with it.

In basic, you tried to use the longer A2 screw in an A1 setup - the reason they tell you it won't work is because you'll slam the bumper on the buffer on the extended screw.

Live and learn.

lakeracer69 · June 27, 2015

Ok, Just saw this. What is the length of the correct screw? I have a PRS stock on my build, but can't remember what I used from 1 1/2 years ago.

God Damn CRS. ::)

blue109 · June 27, 2015

A1 screw works, but the head of a standard A1 screw doesn't sit perfect in the PRS. they came factory with a special Allen head screw with a smaller head. I used an A1 though. Functions fine.

Gunner42 · August 23, 2015

I am having an issue with my AR10 and feeding problems. I broke in my 308 the way it was suggested. I had jam issues from the start. I changed ammo, magazines, had a gun smith look at my rifle, no luck. The jam happens after every 6-8 rounds. It double feeds and even bent a round this last time shooting (22 August 2015). I am attaching a picture of the ammo I used from Lake City Ammunition MFG. anyone can help me with this issue and know who I can contact?

jtallen83 · August 23, 2015

I am having an issue with my AR10 and feeding problems. I broke in my 308 the way it was suggested. I had jam issues from the start. I changed ammo, magazines, had a gun smith look at my rifle, no luck. The jam happens after every 6-8 rounds. It double feeds and even bent a round this last time shooting (22 August 2015). I am attaching a picture of the ammo I used from Lake City Ammunition MFG. anyone can help me with this issue and know who I can contact?

Is this an Armalite AR-10? If it is they will take care of it, ask for Mario, at least he was there to handle things for me a year ago.

What were the suggestions for break-in? Lots of lube I hope?

Is this an actual double feed from the magazine or is the fired case not ejecting?

I'm far from an expert trouble shooter but I know the guys here will ask some of these questions. Some of us Armalite owners are a little possesive of the AR-10 trademark, that designation is reserved strictly for Armalite rifles. Doesn't sound like a big deal but parts compatibility is an issue with the 308 platform.

Edited August 23, 2015 by jtallen83

GRA · August 23, 2015

Right off the top of my head it sounds a lot like part of the problem I was having with my 7.62x39 (I stress "part" of the problem) and it turns out to most likely be the mags.

Are you having this problem when using more than one magazine and/or just one or two mags (and possibly of the same manufacture) or does it happen with rounds #6-#8 regardless of the mags you're using ... ???

survivalshop · August 23, 2015

By double feeding , are you saying two unfired rounds are trying to be fed at the same time or is one a spent round ?

Check your Ejector for proper function , pin is in correctly & may need to change the Ejector Spring . Also check the Extractor for proper function .

Gunner42 · August 23, 2015

Is this an Armalite AR-10? If it is they will take care of it, ask for Mario, at least he was there to handle things for me a year ago.
What were the suggestions for break-in? Lots of lube I hope?
Is this an actual double feed from the magazine or is the fired case not ejecting?
I'm far from an expert trouble shooter but I know the guys here will ask some of these questions. Some of us Armalite owners are a little possesive of the AR-10 trademark, that designation is reserved strictly for Armalite rifles. Doesn't sound like a big deal but parts compatibility is an issue with the 308 platform.

It's a DPMS AR-10 and the break in was after the first 10 Rounds, clean the bore. Each consecutive time up to 50 rounds and then every 25 rounds until 200. I did this and got jams. I read where DPMS said do not foriegn ammo so I stuck with American made ammo. I used plenty of breach and bore lube every time I shot. Being retired army I remember using tons of REM oil on the M16a1, A2, and last the A4. The jams have to be from the extractor pin. Something is not right with it.

jtallen83 · August 23, 2015

So it is a DPMS LR-308 then, not an AR-10. You don't need much for lube in the bore and the chamber, actually any excess should be wiped out, extra lube inside the chamber can cause extraction issues. The BCG should be soaked liberally though.

Is the spent case remaining partially in the chamber or is it fully extracted but not ejected?

Is the issue with one mag or with any mag you try?

I think SS is on the right track, really sounds like an ejection issue but a bit more info is needed.

More pictures of the rifles feed ramps with a mag inserted may help. Take a camera on the next range trip and get a picture of the jam. This will help the pros here diagnose the issue.

98Z5V · August 23, 2015

What brand of magazines are you using? Brand, and capacity...

Edited August 23, 2015 by 98Z5V

TOPAZ · March 18, 2018

On ‎8‎/‎6‎/‎2010 at 1:44 AM, Scottysan said:

I'm having a similar problem with my AP4. Mine's a failure to extract, as is shown by the brass when I get it out. It's notched and even torn some of the case rims.

My gunsmith said the factory chamber polish is fairly rough on these guns, and he can polish it out better without affecting accuracy. He also said an extractor upgrade would help.

I sent my Dpms LR-308 back to the factory after a failure to eject as well as double feed issues, it came back with a note attached that said they replaced the ejector spring with a stronger one and rebuilt the bolt carrier group, now it shoots fine .