Question for LMT owners ...

[Jerry R]

Took the new LMT pistol to the range today. Thought I would only need one magazine for test purposes. Shot great, would not lock back on the empty magazine.

Came home and did some additional testing. Would not lock back on an empty magazine when cycling the charging handle. Hmmmm

Fiddled with the pistol for awhile, then took a look at the magazine. A recently purchased 30 round gen-2 Pmag. Okay, lets try another one ... another gen-2 - same issue. Tried a Colt aluminum 20 round - locked back perfectly.

Okay ... tried a gen-3 Pmag - worked perfectly. Now I'm confused. Tried eight gen-2 Pmags - none worked. Tried a dozen gen-3 Pmags - they all worked.

The magazine followers appear to be the same size and shape, just a different color.

My position on this is that the lower should work the same with any magazine if you are just cycling the charging handle.

The Gen-2 Pmags do not push the bolt catch up at all, much less enough to activate the catch.

The lower is the LMT ambi version. Not sure if the ambi parts are impairing the bolt catch movement. Even if that were true, what could be the follower/spring differences between gen-2 and gen-3 ... not even considering Colt mags and DHS aluminum work it just fine.

I have not contacted LMT yet. Not sure it would be their problem anyway.

Any thoughts or input greatly appreciated.

[Stone]

Pull the lower off and insert an empty mag, one that worked then one that didnt work. See how much the BCR is over the follower. Its possible the bolt catch is out of spec. and its dropping behind it...

"what could be the follower/spring differences between gen-2 and gen-3"

Magpul changed the geometry on the Gen3 so it would work with more platforms or something to that effect. I had just the opposte problems with my ambi LWRC lowers, wont lock back on Gen3 pmaags... There is a noticeable difference between the Gen2 and Gen3. The guarantee that all AR15 mags will work in all lowers is an assumption on our part, not always the case.

[Eric]

My position on this is that the lower should work the same with any magazine if you are just cycling the charging handle. Agreed, of course assuming a proper in-spec mag. I would certainly call LMT and they'll likely be familiar with the issue and may walk through some troubleshooting over the phone.

[SINNER]

The Bolt catch notch on the Gen2’s is flawed. Known to cause issues with many weapons including SCAR’s and HK’s. You can see the difference, one is squared off on the bottom and one is rounded.

[BoilerUp]

All I know is that my NZ MARS shipped with a PMAG gen3 and that's what the NZDF uses. I don't think I even own any gen 2s

[Jerry R]

Pull the lower off and insert an empty mag, one that worked then one that didnt work. See how much the BCR is over the follower. Its possible the bolt catch is out of spec. and its dropping behind it...

"what could be the follower/spring differences between gen-2 and gen-3"

Magpul changed the geometry on the Gen3 so it would work with more platforms or something to that effect. I had just the opposte problems with my ambi LWRC lowers, wont lock back on Gen3 pmaags... There is a noticeable difference between the Gen2 and Gen3. The guarantee that all AR15 mags will work in all lowers is an assumption on our part, not always the case.

Thanks Stone, that was the first thing I tried. BCR rides well over the follower (same amount) on all three generations of PMags. But the Gen-1 and Gen-2 won't lift it.

[Jerry R]

Sinner, took note of that. With the upper completely removed, all three activate the BCR. With the upper installed (without the BCG) when a Gen-1 or Gen-2 is inserted, I can activate the BCR by hand and it has an audible "snap" as it activates; like it is binding on something. But that is not the case with the upper removed.

I have sent a message to LMT via their "Contact Us" form. If I don't get a reply, I will call. Pic below, left to right ... Gen-1 Gen-2 Gen-3.

6578

[FortTom]

I have an older LMT about 7 years old and it cycles with about any mag or ammo I feed it but I've changed the Followers out with magpul and usually just use magpul, all gen 3 or newer.
FT

[Jerry R]

I received a very quick response from Michael Pascuiti at LMT this morning. He basically said what is contained in your responses above ... a known issue, no real fix. He said that even if they shipped some parts and springs, it would not resolve the issue. Nicely stated, and very professional.

So, "It is what it is."

I'll just take the appropriate magazines when LMT goes to the range.

Thanks to all for your input.

[Stone]

I purposely mix in a handful of Gen3 pmags in my mag box for training. They malfunction but I dont know its coming when I am running and gunnin. Keeps me frosty on malf. remediation.:P

I have had nothing but issues withe Gen3 pmags in most of my rifles, piston and DI. The Gen2's have ran flawlessly for me in everything. Its crazy how one guy has them work great then the next poster has nothing but issues. I suppose there is tolerance stacking thrown into the equation as well...

[Stone]

Sounds like you have the same issue I had except with a different gen pmag.

Gen2:
6579

Gen3: BCR drops behind the follower binding it up.
6580

The area on the back of the Gen3 is thicker (on the mag body) which pushes it forward or away from the BCR. They also have more play in the magwell which exacerbates the issue.
6581

[Aragorn]

Well this is all giving me strong second thoughts about purchasing a Mars lower...

[UWone77]

I usually run Lancers in my guns now, also some ETS mags for range use.

Because of this thread, I tried out 6 different Gen 2 mags, only 1 would not drop. I also noticed Hexmags got caught up as well. ETS, Lancers, Gen 3 PMAGs, USGI, Surefire, all ran fine.

[SINNER]

Plastic magazines are only good for stockpiling for panic sales.

[mustangfreek]

Humm...300 dollar forged lower and its picky about mags...lol..no thanks..sometimes I like being poor

[SINNER]

With logic like that, I’d bet you remain poor.


[:D]

[UWone77]

Humm...300 dollar forged lower and its picky about mags...lol..no thanks..sometimes I like being poor

Products that generally have to be designed to accept a wide range of variances is not necessarily a good thing. Prime example, having your gun work with cheap steel case ammo to match grade ammo. Low end AR barrels all have their gas ports opened up, so bubba shooting his Tula ammo doesn't complain his gun doesn't work.

There is nothing wrong with the MARS Lower. It's actually closer to $200, and has full ambi controls. It's actually not a bad deal if you account for the features.

[fledge]

Humm...300 dollar forged lower and its picky about mags...lol..no thanks..sometimes I like being poor

Maybe that’s why mil took forever to approve pmags.

[BoilerUp]

Humm...300 dollar forged lower and its picky about mags...lol..no thanks..sometimes I like being poor

Or maybe it's actually "10 dollar plastic mags and they're picky about receivers"?

[Stone]

I usually run Lancers in my guns now, also some ETS mags for range use.

Because of this thread, I tried out 6 different Gen 2 mags, only 1 would not drop. I also noticed Hexmags got caught up as well. ETS, Lancers, Gen 3 PMAGs, USGI, Surefire, all ran fine.

Yeah I have been meaning to pick up some metal mags just to mix it up a bit. Thinking about the Okay Ind. and some of the FN mags Sinner had mentioned that were ultra reliable. Pmags are like bic lighters, disposable...

[Stone]

Well this is all giving me strong second thoughts about purchasing a Mars lower...

I wouldnt sweat it brother, worst case scenario is it doesnt lock back after the last round. All the more reason to do a chamber check before swapping mags. LMT makes some quality gear. I wouldnt put this on them because I am pretty sure your lower is well within spec. Magpul wanted the best of both worlds but that just isnt going to happen...

[Jerry R]

I wouldnt sweat it brother

Not a problem here, just wanted to run this by the clan. Current inventory is 178 AR magazines (not counting 308 mags), and only 24 are Gen-1 or Gen-2 PMags. Just wanted to be sure it was not something I did, or if it was a known issue.