LR-308 issues

[Dustoff82]

So, as a disclaimer this is my very first ar-308 pattern rifle. I have been shooting ar-15s for years and do 3gun.


I just recently purchased a DPMS Recon 16" barrel in .308. I am currently at my local range and am having a slew of issues. I am having FTF, FTEs and an occasional jamming of the Bcg. I purchased 2 pmags from midwestpx and had them cut them down to 5 rounders for me. I am also using Hsm .308 168gr hpbt bullets. Dang near every round is either a FTF or FTE.

Anyone have any idea what could be happening or is wrong? Thanks for yalls help!

 

[Eastbay]

Are you using brass or steel cased ammo? Wondering of your spring was trimmed too much behind the follower.

 

[Dustoff82]

Brass ammunition. I also have a PRI gas buster CH and a Gieselee sd-c trigger.

 

[BLDTYLRY]

Have you tried using a standard 20-rounder?

 

[Longshot38]

My DPMS did not like the metal C-product magazines in the least. With those FTF was a fairly common issue. Once I starting runnig Magpul magazines those issue went away.

 

[BCP]

So, as a disclaimer this is my very first ar-308 pattern rifle. I have been shooting ar-15s for years and do 3gun.


I just recently purchased a DPMS Recon 16" barrel in .308. I am currently at my local range and am having a slew of issues. I am having FTF, FTEs and an occasional jamming of the Bcg. I purchased 2 pmags from midwestpx and had them cut them down to 5 rounders for me. I am also using Hsm .308 168gr hpbt bullets. Dang near every round is either a FTF or FTE.

Anyone have any idea what could be happening or is wrong? Thanks for yalls help!

My first thought is your magazines. Not sure what you mean by jamming the BCG do you mean it's in battery with a round in the chamber or ??????

 

[Dustoff82]

In battery. It wouldn't kick out the round, and the Bcg would be jammed up. I also tried firing without a magazine and had a FTE.

I do not have any 20 rounder magazines, so I can't test them, and I did not bring the 19 rounder dpms mag. I will add though, I think those 5 rounder magazines were not helping. They both seemed to be sticking, although one was better then the other.

 

[BCP]

You need to get some different mags and ammunition to help eliminate those two factors. After that I would be inclined to think headspace (since they are sticking in there and not cycling).

 

[Dustoff82]

Will do. I'll try that next week.

 

[MidwestPX]

In battery. It wouldn't kick out the round, and the Bcg would be jammed up. I also tried firing without a magazine and had a FTE.

I do not have any 20 rounder magazines, so I can't test them, and I did not bring the 19 rounder dpms mag. I will add though, I think those 5 rounder magazines were not helping. They both seemed to be sticking, although one was better then the other.

If it's failing to eject without a mag in place, I don't think it's a mag-related problem. Can you expand more on what you mean by the mags "sticking"?

I happened to come across this post and wanted to help troubleshoot. I've actually never had any reports of feeding issues with the cut-down mags that were ultimately the fault of the magazines (mostly underpowered ammo) and we went through 1K of them in about 10 days earlier this month so there are a bunch of recent production mags out there.

So when you started using standard 20LR PMAGs, your FTFeeds went away but you continued to have FTEs? How well lubed is your BCG?

 

[Soct]

What bolt?

 

[Dustoff82]

@ THT: The followers are sticking inside the mag. Both do it, but one is slightly better then the other. I did not have a 20 rounder on me, nor do I have one, but I was only using the 5 rounders. As to the BCG, and the rifle in general, I oiled it quite a bit.

To sum up my shooting experience today, If I pulled back on the charging handle and let the bcg slam home, the first round would always fire. The FTF/FTE was usually after the first shot was expended and the gases/magazine was doing the reloading. The FTE were with and without the mags.

 

[Dustoff82]

@ SCOT: THe Bolt is what came with the rifle, a dpms.

 

[MidwestPX]

@ THT: The followers are sticking inside the mag. Both do it, but one is slightly better then the other. I did not have a 20 rounder on me, nor do I have one, but I was only using the 5 rounders. As to the BCG, and the rifle in general, I oiled it quite a bit.

To sum up my shooting experience today, If I pulled back on the charging handle and let the bcg slam home, the first round would always fire. The FTF/FTE was usually after the first shot was expended and the gases/magazine was doing the reloading. The FTE were with and without the mags.

Yeah, factory 20LR PMAGs (can) do that. It's usually within the first inch of the magazine body where the follower can stick at an angle. If you want to send them back, I can put rounds through them with our .308s to see if they're defective or not. But if you're having ejecting problems without a mag, that points to a gas system issue.

 

[Woody67]

By the sound of things it's a gas problem. Check your gas block to make sure it's tight. If it is adjustable then open it up some more. If its not a adjustable pull it loose and make sure the port in barrel is lined up w gas block port. Just worked on a ar10 for a friend that he had same problem. Was not getting enuf gas to move carrier properly. Would not hurt to check gas key on top of carrier too. Woody

 

[Thumper580]

Agree...check gas port alignment.. If OK I might throw a possible rough chamber, unlikely but possible. What do the spent cases look like?

 

[Dustoff82]

[MENTION=24411]THT[/MENTION]: I appreciate the offer. If you don't mind, I'm going to try to get my end situated first and if I'm still having issues with feeding then I'll send them in. Don't want you to waste time of money if its my rifles fault.
[MENTION=1579]Thumper[/MENTION]: the spent casings are not dented or show any major signs of damage, but they all to some extent have scratches on them.

 

[Dustoff82]

@ woody, I just had my PRI 15" rail put on and my rifle does not have an adjustable gas block. I will take it back to the gunsmith and have him look at it. This was my first time firing it, I did all the mods first.

 

[MidwestPX]

Agree...check gas port alignment.. If OK I might throw a possible rough chamber, unlikely but possible. What do the spent cases look like?

Gas block alignment, ID of the block, OD of the seat, gas port size, and gas key are what I'd look at it specifically. On another forum, a poster with a brand new DPMS .308 discovered his gas port was severely undersized. Opened it up to spec and it ran like a champ.

 

[MidwestPX]

[MENTION=24411]THT[/MENTION]: I appreciate the offer. If you don't mind, I'm going to try to get my end situated first and if I'm still having issues with feeding then I'll send them in. Don't want you to waste time of money if its my rifles fault.
[MENTION=1579]Thumper[/MENTION]: the spent casings are not dented or show any major signs of damage, but they all to some extent have scratches on them.

No problem. Please keep me in the loop.

 

[AKONA]

The DPMS factory magazines need new followers. At least the ones I got the followers are plastic garbage and will drag and tilt head down.
When debugging a FTF issue try to cycle a few dummy rounds manually and in slow motion. If one can see any frictions or mag
issues in slow motion one can assume some of these issues might be only amplified by the regular fast cycling of the action.
With a full magazine hold the mag catch while firing to make sure the bolt will stop at the catch. This will quickly tell you if
the bolt is getting at least that far but ideally you want the full momentum to strip a fresh round when the magazine has
the most tension that is when it is fully loaded.
Also watch our for those burrs and steps in the extension/receiver joint and consider polishing the feeds. A problem here might
be accentuated by the use of hollow points.
I hope this helps.

 

[AKONA]

Sorry I saw you have FTE too. I suggest before you consider potential undergassing issues also make sure you do not have any unnecessary frictions, excessive tension
from the magazine or hammer and everything should be running smoothly. Also make sure the bleeding hole in the buffer tube is up to spec and not obstructed.
Any firearm that runs smoothly with less gassing is going to potentially last longer and in some cases be more accurate.

 

[Casey Simpson]

Ammunition. What kind are you using? Federal Gold Medal Match, similar ammo, or Lake City Match, all in either 168 or 175 grain should function flawlessly in your rifle.

Lubrication. What kind are you using? Any engine motor oil, or white, amber, green, beige, red grease is required on the buffer spring, carrier, cam pin and cam area, bolt and all its parts/lugs.

Lubrication. Amount. The parts should glisten, but not drip, lubricant. Liberal application is the standard.

Parts. Changing the extractor remedied one of these problems for me. Polish the parts: extractor, ejector, bolt lugs, bolt face, carrier bearing rails, gas key bearing on the charging handle, not removing metal, but simply the applied factory finish which will get removed with use anyway. Make the surfaces shine with 800 grit high quality paper lubricated with oil. Polish the top of the hammer bearing on the carrier.
Buffer Spring. Replace the factory one with a Tubb CSS.

Chamber. Inspect, polish, and clean....after each firing session though the barrel does not require such regular cleaning. The chamber does.

One of the better authorities on AR's is Glenn Zediker. Read his material. He draws from Tubb, Madesha, KAC and others.

Let us know what you discover.

 

[Soct]

Where in TX are you? If you are close to me I can probably help you better in person. I got some proven mags and some spare parts that will fit your rifle. We can do some troubleshooting.

 

[Skeld1]

Sorry to hear of your trouble. Just to let you know, there is hope. I have the same rifle and have run about 300 rounds of PMI and Tula through it and it hasn't malfunctioned once...I also haven't really cleaned it thoroughly but I have lubed it some, but not a lot. It isn't a finicky rifle if it is running the way it should. Something must be off.

 

[bigmatt17073]

I had some FTE and FTF problems early on with my DPMS LR308 as well. I attributed to the ammo being used and it being new. After getting fed up with the problems and not having any other ammo I packed it up and headed home. Once home I cleaned it and polished up the BCG (parts mentioned a couple of posts up) to smooth out the action. The BCG was well lubed next time out. I have had zero problems since the initial polish and lube. I now have a few hundred rounds down range with it and haven't had any trouble since that first incident. Today, I even hit the range with it using the previous problem ammo (CBC/Magtech 7.62x51 M80 ball), and even after a full box of it everything worked perfectly.

 

[Soct]

I had some FTE and FTF problems early on with my DPMS LR308 as well. I attributed to the ammo being used and it being new. After getting fed up with the problems and not having any other ammo I packed it up and headed home. Once home I cleaned it and polished up the BCG (parts mentioned a couple of posts up) to smooth out the action. The BCG was well lubed next time out. I have had zero problems since the initial polish and lube. I now have a few hundred rounds down range with it and haven't had any trouble since that first incident. Today, I even hit the range with it using the previous problem ammo (CBC/Magtech 7.62x51 M80 ball), and even after a full box of it everything worked perfectly.

I had the same problem with mine after I got it build. All the tolerances were tighter than a gnat's ass. A good polishing of every moving part and bearing surface and it was a whole different gun.

 

[Nihonjin]

@ woody, I just had my PRI 15" rail put on and my rifle does not have an adjustable gas block. I will take it back to the gunsmith and have him look at it. This was my first time firing it, I did all the mods first.

Key factor which you failed to disclose on your initial post. You gave readers (myself anyways) the impression that the rifle was a factory fresh DPMS Recon and you were using them with modified magazines.
Given this new piece of information, I agree with others that suggested gas system. Your gunsmith had to remove the gas system to install your new rail. The gas block is probably misaligned.

 

[Casey Simpson]

Despite the wild goose chase / red herring, polish the bearing surfaces.

 

[Dustoff82]

@scot: I live in the dfw area. To everyone else, thanks for your input.

 

[M60Jockey]

My Recon failed me as well. Turns out the gas block slipped out of position. Had it repaired and sold it. Shame. It was super accurate, but unreliable.

 

[codemancode]

Had the same gun with the same issues. Gas block misalignment and crappy magazines were the issue. Replaced the gas block and mags and the guns worked perfectly since.

 

[sentry1]

I had this same problem with a Mega MATEN. I tried everything, changed mags, changed ammo, called up Mega Arms, called up JP about the BCG, called up Seekins about the gas block...

In the end, it was a simple problem of break in for me. Someone made the suggestion: Lube the gun. Lube the gun a LOT. Get it sloppy wet to where it's dripping out of the gun. Run some ammo through it.

I did just that. Lube dripping out of the gun, put 50 rounds of 147gr ball ammo through it, took it home, cleaned it out, added a normal amount of lube (be a little more generous with the lube than you would with an AR15), and it now runs like a champ.

So, try lubing it up like a (insert hooker joke here).

So, as a disclaimer this is my very first ar-308 pattern rifle. I have been shooting ar-15s for years and do 3gun.


I just recently purchased a DPMS Recon 16" barrel in .308. I am currently at my local range and am having a slew of issues. I am having FTF, FTEs and an occasional jamming of the Bcg. I purchased 2 pmags from midwestpx and had them cut them down to 5 rounders for me. I am also using Hsm .308 168gr hpbt bullets. Dang near every round is either a FTF or FTE.

Anyone have any idea what could be happening or is wrong? Thanks for yalls help!