LMT 10.5" upper designed for suppressor?

[khc3]

I recall reading somewhere that the LMT 10.5" upper is set up to be best used with a can.

Is there any truth to that?

Thanks!

[AR15barrels]

I can confirm that they use a significantly smaller gas port than Colt and others do on 10.5" barrels.
I can also tell you that this MAY cause short stroking with heavier buffers.
Both of these are signs that the LMT 10.5's would be best served with a KX3 or suppressor installed.

You certainly do NOT need or want to use a heavy buffer with an LMT 10.5" barrel.

[grinch]

LMT made the navy MK18's and yes they stepped down to a .069-.071 gas port but we have run them hard for a long time with heavy buffers with no issues. The initial test I read on there development there was no use of a suppressor or was there any designing it for a suppressor but it was confirmed it could use the SOPMOD can as well as that it would function with all ammo that was in the system prior to deployment.

[KevinB]

I've run LMT 10.5 with and w/o suppressors with H and H2 buffers...
No worries.

and NO KX3

[shark31]

I run a 10.5" LMT with a H buffer installed. I have no problems either.

[AR15barrels]

Everytime this comes up there are always incidental reports that "I run mine with an H buffer and it works fine" but these reports do not take into account how many rounds the operating spring has on it and what ammo is being used.

With my experience of selling LMT's 10.5" uppers and hearing from customers, I have specific data points that I reference.

If you start with all new parts (upper, bolt, carrier, operating spring and h-buffer) and run any ammo other than full power stuff without a KX3 or a can, there's a good chence that you will see short stroking.

Change anything listed above and the results are different.

[KevinB]

I dont want this to evolve into a pissing contest.
But I've had 5 different LMT 10.5's, teammates have had several, and civie friends have a few. All in all more than 30 that I have seen through down a few rounds.
All started NIB - several run on Colt M4A1 Property US Gov't lowers.
The ONLY time I've had problems was adding a LMT "Enhanced" Bolt then unsuppressed two gagged and choked and basically shit the bed.

I only have run M855 and Mk262 thru them, and I dont recall seeing anyone else running anything esle. For those people shooting SAAMI spec ammo - I have no guarantees - but my "guess" would be LMT did not build it for them...

*edit - one friend was trying to shoot 45gr Winchester that would not run with it.

[AR15barrels]

I only have run M855 and Mk262 thru them, and I dont recall seeing anyone else running anything esle. For those people shooting SAAMI spec ammo - I have no guarantees - but my "guess" would be LMT did not build it for them...

*edit - one friend was trying to shoot 45gr Winchester that would not run with it.

Thank you for proving my point.

[AR15barrels]

All started NIB - several run on Colt M4A1 Property US Gov't lowers.

Did you install brand new operating springs in those lowers at the time you put the 10.5" upper on them?

[KevinB]

My bad - reading is fundemental...
I never think about people not shooting NATO pressure ammo

[AR15barrels]

I never think about people not shooting NATO pressure ammo

There are a bunch of people that do not shoot full NATO pressure spec ammo and want their guns to work with ANY ammo.
These people should not be running an H-buffer with a 10.5" LMT upper.

[Aubrey]

Randall,

If I wanted to use a 10.5" (or is it 10.3"?) LMT Upper to shoot BOTH SAAMI-spec .223 55gr FMJ AND NATO-spec 5.56x45 Mk262, is there a combination of gas-port diameter and buffer weight that you know would work?

My inclination would be to use a Noveske KX-3 and conventional M4 bolt carrier with this upper.

Many thanks for your feedback.

[AR15barrels]

Randall,

If I wanted to use a 10.5" (or is it 10.3"?) LMT Upper to shoot BOTH SAAMI-spec .223 55gr FMJ AND NATO-spec 5.56x45 Mk262, is there a combination of gas-port diameter and buffer weight that you know would work?

My inclination would be to use a Noveske KX-3 and conventional M4 bolt carrier with this upper.

Many thanks for your feedback.

A KX3 should make it work with any ammo.
Try it with an H-buffer and drop back to a standard carbine if it short strokes.

[S-1]

I use a H buffer with my LMT 10.5". It's functioned great with and w/o the can using M855, M193 and AE .223. It did not function at all with the newer PMC 223 (very weak) unless I had the can attached. I ended up giving the PMC to my BIL to use in his over gassed Bushmaster 11.5".:D

[CarlosDJackal]

FWIW, I had originally installed a KX3 on my SBR (with 10.5" LMT upper). But since I could not take it apart to clean it, I have since re-installed teh A2 FH and have not had any issues whatsoever.

[Daveo]

I have a 10.5" LMT that runs well on XM193 (Federal and Prvi Partisan) Rasway Green and M855 (obviously). It has also run fine on some cheap local reloads, PMC and even some Wolf. I would say I have probably 2000 rounds down the tube, all with an H buffer. With the SAAMI stuff, the gun would not short stroke when fired fromthe shoulder but short stroked a couple times when I tried shooting the rifle with my right hand only. Maybe I got lucky?

[grinch]

Very true Randall I guess I dont consider shooting anything but military ammo through them. I do agree that a gun and ammo need to be considered as one system and this is very over looked. guys need to realize the guns they get have limitations and shooting shit ammo through a short barrel is going to cause problems.

If your going to add a KX3 just get a longer barrel get the added velocity

[KevinB]

If your going to add a KX3 just get a longer barrel get the added velocity

I agree wholeheartedly on this.

[Wraith]

Hi guys, this is my first post here and you've got a great website. I post under the same name over at silencertalk.com but I've been getting more and more into ARs. I figured this would be a good place to post and ask questions and if you're wondering, rob_s is the one that provided the link to get me over so you can blame him.

I've got an LMT 10.5 and it's by far my favorite AR that I own. I run it with a suppressor (AAC M4-2000) and it doesn't get anywhere near as dirty as my other ARs do with the same suppressor. I also run an H2 buffer without any problems but I only run NATO spec ammo through it which is probably why I don't have any problems. In any case I don't know if LMT SPECIFICALLY had suppressor use in mind but since it seems to work so well I'm not going to look a gift horse in the mouth.

[AR15barrels]

I've got an LMT 10.5 and it's by far my favorite AR that I own. I run it with a suppressor (AAC M4-2000) and it doesn't get anywhere near as dirty as my other ARs do with the same suppressor. I also run an H2 buffer without any problems but I only run NATO spec ammo through it which is probably why I don't have any problems. In any case I don't know if LMT SPECIFICALLY had suppressor use in mind but since it seems to work so well I'm not going to look a gift horse in the mouth.

They did specifically have the suppressur use in-mind.
That's why the gas port is smaller.
The fact that your action stays clean supports the fact that you have it properly setup.

Any AR that has extraction ills, excessive recoil or runs really dirty is probably unlocking pre-maturely.
Of course some of these over-gassed symptoms are used in support of the gas piston as well.
It's really just a matter of choosing the right ammo and buffer configuraton and direct impingement AR's should run pretty clean.

[Wraith]

They did specifically have the suppressur use in-mind.
That's why the gas port is smaller.
The fact that your action stays clean supports the fact that you have it properly setup.

Any AR that has extraction ills, excessive recoil or runs really dirty is probably unlocking pre-maturely.
Of course some of these over-gassed symptoms are used in support of the gas piston as well.
It's really just a matter of choosing the right ammo and buffer configuraton and direct impingement AR's should run pretty clean.


Would you happen to know if the LMT 14.5" upper is designed the same way? I had a no name 16" M4gery upper that was super dirty no matter how heavy of a buffer or different kinds of ammo that I ran through it. I basically gave up on it and got rid of it cheap. Like they say though, buy quality once. I would like to put together another Mgery and was thinking the LMT 14.5" might be the way to go. I run a suppressor more than not so my main concern is keeping the gun as clean as possible with a suppressor.

[AR15barrels]

Would you happen to know if the LMT 14.5" upper is designed the same way? I had a no name 16" M4gery upper that was super dirty no matter how heavy of a buffer or different kinds of ammo that I ran through it. I basically gave up on it and got rid of it cheap. Like they say though, buy quality once. I would like to put together another Mgery and was thinking the LMT 14.5" might be the way to go. I run a suppressor more than not so my main concern is keeping the gun as clean as possible with a suppressor.

LMT's 14.5" and 16" have gas ports similar to Colt and others.
If you get a 14.5" or 16", I recommend the LMT enhanced carrier as it will delay the unlocking of the action, giving more time for the bullet to get out the front of the barrel/can.

The reason some AR's run so dirty is that the action is unlocking before the barrel pressure subsides.
This leaves the chamber open to vent the barrel gasses into the action.
If you open the chamber later, most of these gasses have already run out the front of the barrel.

The use of a suppressor makes this problem worse because it holds the pressure longer than a plain barrel does.