LMT MWS / PMAG Jam Question

AR/M4 Beyond 5.56/.223
1

Sorry in advance for the long and pic heavy post:

Searched and didn’t find anything like what I’m experiencing. I found this today when my father and I were shooting. We mounted his scope on his gun which is the exact same as mine. We purchased them 2 weeks ago.

Details:
LMT MWS 16" CL barrel
100 rounds down range on mine / 25 down range on my fathers
0 FTF / FTE issues to date
Tack drivers that can far outshoot our abilities

All I’ve done thus far is load and shoot 3 shot groups until empty. I finally had a situation that req’d dropping the mag with rounds left. I hadn’t toyed with it yet so I just realized the issue.

Now, the problem

Received new G3 PMAG LR/SR 20’s in the mail friday.

Loaded with Federal .308 rounds to sight in his gun today.

These new mags are significantly tighter to get in the mag well than the ones that came with the guns (also pmags)

0 FTF / FTE during shooting (In either guns even when shot as fast as we can)

When done he had a rounds left in the mag

here’s where the issue started

Hit the mag release and it wouldn’t drop the mag. Jammed in the receiver.

Tried pulling the charging handle and it was locked up tight. Finally it took extreme force to get it barely open to roughly 5/8" back.

Smacked the mag well a few times and the mag finally dropped

Tried the charging handle again and nothing doing.

Used my knife tip to barely put pressure on the bolt that I could see and it finally came back with a hard tug on the charging handle.

Had to use so much force it threw the round a country mile.

Tried to see if it would do it again and it did. This time when I got it open it left the round in the chamber. Closed the bolt and then pulled hard as heck again and it pulled the round out.

Thought maybe it was just dry so advised my father to lube the snot out of it when he got home.

Seeing that mine has had zero issues I’d see if I could get mine to replicate it. Well it sure did.

Got home and pulled mine out of the safe, cleaned, and lubed good. Loaded a few rounds in a G2/Standard/Original whatever model comes with the gun and a few rounds in the G3’s we just got.

Mine did the exact thing his did with either mag (except the G3 mag was harder to eject and the G2 mag came out silky smooth). Every issue the same as described above.

I tried to rack and eject shells fast with a well lubed gun. I had multiple jams where the gun didn’t eject the round in time while loading the next in the chamber.

One jam was so bad that the round was jammed with the bullet tip pointing at the 8 - 9 o’clock position on the feed ramp on top of the round in the barrel so tight that when I dropped the mag, pulled the charging handle, it pulled the bullet out of the casing thus spilling all the powder in my lap.

All the other bullets have markings on them from feeding, etc. It’s marring the rounds with gouges and fine scrapes.

You can see the mark where the bullets jammed on the feed ramp in an over under fashion. The one feeding would jam on top of the one trying to be ejected (i didn’t get a pick of the jam):

](http://s43.photobucket.com/user/tmeurlin/media/1F58B8E3-733B-4383-B0A2-2C35DC5ECD23-8683-00000692D550C52F_zpsc2891b6c.jpg.html)[/IMG]

here are pics of my BCG. Please let me know if you see anything out of line. The lube made it look dirtier. I have not stripped it down adn cleaned well. Only lubed it.

](http://s43.photobucket.com/user/tmeurlin/media/B7727A6F-1C50-4CE2-9930-E270AA21FE4D-8683-00000692C51308A3_zpsea86d579.jpg.html)[/IMG]

](http://s43.photobucket.com/user/tmeurlin/media/847688FB-C348-4914-A263-9D4F15A24C0C-8683-00000692BBE21448_zps2a442548.jpg.html)[/IMG]

](http://s43.photobucket.com/user/tmeurlin/media/6321ACF6-E3EF-4F06-8B19-C1C969684696-8683-00000692E735461E_zps53c85b06.jpg.html)[/IMG]

](http://s43.photobucket.com/user/tmeurlin/media/E389BF06-0779-4AC7-95C9-A84293A99F7B-8683-00000692F599D0E7_zpsb7ec1e0b.jpg.html)[/IMG]

](http://s43.photobucket.com/user/tmeurlin/media/DA94BE62-FBC2-46D9-B452-E051554162F8-8683-00000693034BD403_zpsbe3a88df.jpg.html)[/IMG]

](http://s43.photobucket.com/user/tmeurlin/media/5906CB9E-17FC-426B-9B9B-DA78131ED11D-8683-00000692FC52C1BC_zpsf3952989.jpg.html)[/IMG]

2

should mention again that when running the gun it functions flawlessly. This issue has only come up when trying to drop a mag with rounds left.

These guns are tack drivers. Easily shoots in the same holes repeatedly. Even my pops’ 62 year old bad eyes it’s touching holes.

Incredible rifles. Just need to figure this issue out. it will be a big problem while hunting and trying to drop mags after a hunt or other scenarios.

3

Man, it sounds like you got a lot going on there!
Make sure you don’t ride the charging handle forward at all, that can give you that issue with the crooked round.
The sticky bolt could be a dimension issue, chamber and/or brass. What ammo are you using? Have you tried multiple brands of factory ammo? Was any better than others?
If all the gen 3 mags have issues inserting or removing them from the magwell while the others are fine? I’d call Magpul on that. I’d also look for evidence of any marks on the mags from the well or the carrier.

4

Answers / Questions above.

5

When you have the charging handle back all the way, just release it, don’t let your fingers slow it down at all.
Ok, from here, I’d contact LMT and Magpul, give them some time to see what they want to do. Report back when they’re done.

6

With my LMT MWS, if I “tap” the magazine base after it is inserted into the rifle, some of the P-MAGS stick as you have described - not the newer P-MAGS. The “smacking” of the bottom of magazine after insertion is done to ensure seating. If I don’t “tap” then magazines do not stick. Decided not to “tap” anymore - unless it is an M14/M1A.

7

There are some Pmags that will over-insert into the magwell. Not sure what GEN magazine but I think Magpul addressed this issue.

Also, occasionally when I try to extract a chambered round it takes a little force on the charging handle to pull the BCG back and extract the round. Not crazy force but a little more than my regular AR-15 rifles. When this happens, I just add a little more lube on the BCG. Since these are new rifles, I suspect things will loosen up after a few hundred rounds.

8

Update:

tonight I checked the mags and seems to be all set in that regard. I wasn’t able to do a speed rack test b/c I couldn’t get the charging handle to work with a live round. That said there were no jams during normal cycling which is better than last night. I will speed test again when I get the charging handle issue resolved.

When i have a mag inserted and a round chambered I have to pull back with all my might and the charging handle still won’t come back. It doesn’t budge. I got the round to eject 1 of 3 times with the mag inserted.

I have to drop the mag to eject the round consistently. Even at that I need to pull back with significant force to make it work. That is bizarre to me and doesn’t seem like a break in issue. I mean I have to put a ton of force on it.

I did speak with Gene today at length and he said to shoot it a bunch and it’ll work itself out. I trust him but this seems to be firmer than what’s detailed on the web and what he said.

See this old thread from the summer as reference:
https://www.m4carbine.net/showthread.php?t=134974

Thoughts?

9

Gene at LMT is a great wealth of information. He’s a 100% guy that wouldn’t steer you wrong.
I’ve heard of some really fresh guns that did similar, but not as extreme for clearing the chamber. Maybe, it’s a stack up of tolerances that need to be worked in. I do know of an example that took a couple hundred rounds to smooth up. Some guys also complained about the difference in feel switching to the dual ejector, maybe that’s part of this?
What did Gene at LMT say?

10

Gene said to run the snot out of it and it would loosen up. Seems strange that it’s this tight. I’ll take his word for it but we’ll see. He’s been very helpful thus far.

11

Well…
Run some more rounds and see if it makes a difference, then you’ll know.

12

while not the same issue, i did have an issue with 1 of my early generation Pmags not allowing my bolt to completly close on a full mag. durring function testing, i didnt notice it any more difficuly to extract a round from the chamber if there is a mag inserted or not.

still have a bunch of 308 pmags, but stick to using knights mags for now

13

i’m finally going to get to shoot these things a lot on Thursday. In the meantime I figured I’d check to see how tight the bullets were in the chamber. I locked the bolt back and placed the round in the chamber. I then turned it upside down to see if the bullet would fall free. It did not. Tight as a tick. I closed the bolt, pulled hard on the charging handle and it came apart just like it occurred earlier with the mag installed. This was detailed in the pics above.

What I realized is that the round (round 1) I used was one of the test rounds I had been using. Over time on my test the gun had loosened the bullet to where it fell apart. I cleared the bullet from the chamber carefully with a cleaning rod. I then cleaned up all the gunpowder…again…this is getting old.

I did another test with an untouched round (round 2) and it stuck as well. That round ejected after a hard pull on the charging handle. I compared that round (round 2) to another untouched round (round 3) and round 2 is now a hair longer (visible to the eye) than the round 3. All rounds are 150gr so they’re not that long.

I still plan on shooting these a bunch on thursday per gene’s instructions.

I would however like any input on the matter if you think the tightness of the chamber is correct. Thanks in advance.

14

Do you have a chamber brush? Make sure that’s clean.

15

I do not. the pic above it appears pretty clean.

that said, I inspected/tested my brothers which was bought at the same time and is unfired. His was the display model at the LGS. His is really tight as well in all the same tests (pulling charing handle while gun is clear / with mag inserted and round chambered / drop mag and round chambered) but not as tight as mine or my fathers. Being the floor model it’s been worked significantly more than ours and therefore a little broken in. As such, I think Gene is right (I have no reason to doubt him) and will find out more after I shoot 250 round out of each Thursday.

I really hope these don’t have to go back with deer season starting on saturday.

16

A chamber brush is something you need anyway, plus they’re relatively cheap. If I were you, I’d get one ASAP, you’ll just run into further problems if you don’t.

17

Dewey makes a whole .308 AR chamber cleaning kit for like $35 that works very well.

18

will order. thanks for the heads up.

19

Something else you can do is get a Sharpie marker and blacken the neck and exposed projectile. Chamber and eject it, look for witness marks. With live ammunition, do this at the range in a safe manner. I always handload up a dummy when I do this. Something else to consider is to always load .308 ARs from the magazine. NEVER start a round in the chamber by hand and hit the bolt release to let the BCG fly home. THEY CAN FIRE. Trust me, I’ve seen it.

20

good advice. thank you.

what do you think about the round not falling out of the chamber? I figured it would be tight but that the round should fall from it with some ease.

That’s what led me to close the bolt on it so I could extract it. I didn’t want to put a cleaning rod down the barrel and compress the bullet/powder and risk that. Now I know both are not safe.