LMT 10.5" Set-ups

General Firearms NFA
1

I have a LMT 10.5" and took it out for the first time this past weekend. It was a blast. Anyway, I was having trouble running Wolf ammo through it and now I am trying to figure how to fix it.

So, I am asking if you have a LMT 10.5" AND you can run Wolf through it, please post your specs so I can see what works. Also if you ran other ammo first to break in the weapon please tell what you used and how much of it.

Thanks in advance.

My specs:

Upper
LMT 10.5"
Standard Handguards from a Stag
LaRue rear BUIS
LMT BCG
CMT Charging Handle
Standard FSB

Lower
Sabre Defence Reciever
Stag LPK
Magpul Ctr stock
Stag buffer tube
H buffer
Tubbs ISMI Spring

2

Does the bolt lock open on the last round? If not, use a standard carbine buffer.

3

First things first. LMT uppers are made to run with mil-spec ball (M855 in particular). Because of this, they have smaller than usual gas ports. Wolf is the most under pressured ammo on the planet.

So how to make it work? Well first, ditch the ISMI spring and H buffer and go back to a cheap $5 buffer spring and carbine buffer. Or stick with mil-spec ammo and keep the better spring and buffer.

C4

4

I have a 12.5" SBR that will not run SAAMI spec ammo with an ISMI spring and an H buffer, but will run with a std carbine spring and an H2 buffer.

I think those ISMI springs are a lot stiffer than most people think. That would be the first thing I’d ditch.

5

I had AR15barrels.com open up my gas port on my 10.5 to get 223 pressure ammo to work. Works great now. Mine would not shoot with a standard spring and buffer. But if I were you I would try going back to the standard spring and buffer before you have anything drilled.

6

Yeah, but they won’t shrink just sitting in the safe. :wink:

7

Believe me Aubrey, I want that ISMI spring to work, but it’s just been a no-go in the SBR’s I’ve tried it in. I admit I have been thinking about cutting a coil at a time off it 'til I get it to work, though.

8

Try the most probable & inexpensive solution first, with a standard $5 action spring, and the standard, non “H” buffer.

9

The fix is very easy, stop shooting Wolf crap-ammo through your SBR!! Why in God’s green earth would you run the cheapest ammo you can find through a gun thaat you have already invested a lot of your hard-earned money in is beyond me. This is like buying an expensive Ferrari and feeding it fuel from the mom-and-pop gas station who bought all the leftover gasoline from the shady truck driver!! :confused:

FWIW, I’ve had absolutely no issues with UMC or S&B 55-grain ammo. YMMV.

10

To everyone with suggestions, I appreciate them and I will try them.

For those of you that are not making suggestions or have a problem with giving an actual answer to my problem please refrain from posting. Also I suggest that you reread my original post if you need any clarification. If I want to run Wolf, that is my choice.

11

Here is what I have and what has worked for me.

10.5" LMT
Standard spring
Carbine buffer

Ammo that works 100%:
XM193
XM855
MK 262 MOD 1
Black Hills .223 55gr FMJ Red Box

Other types of Ammo and issues I’ve had:
TAP FPD .223 75gr - won’t lock bolt after last round/FTF
Hornady .223 75gr Match - won’t lock bolt after last round/FTF
Wolf .223 55gr polymer coated case - won’t lock bolt back

I broke in the barrel using 60rds of TAP FPD and 300rds of Federal XM193. The FTF w/ the TAP and match rnds only happened on my last range trip. I don’t know if it was the mags or the ammo. Which Wolf cartridge are you using? Is it the steel case or the brass case? I only used about 60 rnds of the wolf steel case and I would suggest that you stop. Short barreled ARs send a lot of shit back into upper and lower receiver and it is a fucking pain in the ass to clean afterwards. YMMV.

Marco

12

Sorry. I have an LMT 10.5, but none of my firearms ever see Wolf ammo. Why buy top notch gear and feed it bullshit?

13

At least you’ll get good malfunction clearance reps…:wink:

14

My LMT runs on everything I’ve put through it including Wolf.

My gun:
10.3" LMT bbl, upper receiver (cutdown factory LMT 14.5" w/gas port work via Randall Rausch) I did run my 5.56mm NATO neck and throat reamer through it
Colt M16 carrier w/CMT bolt w/Crane O-ring
KAC RAS2 w/KAC foward grip
Aimpoint M2 w/LaRue RAS2 mount, LaRue BUIS
PRI gas buster CH
LMT lower receiver w/standard trigger
VLTOR receiver extension w/Magpul CTR stock
CMT H2 buffer w/chrome silicon standard rate buffer spring

15

No problems here with my 10.5" LMT and Fed XM193 or wally world special rem umc 223.

16

While I haven’t had a chance to fire my 10.5 LMT upper. Did anyone try Federal 55 and 62 grain .223 through their upper.

17

They also don’t have to be changed out as much as standard springs do and you don’t have to worry about your bolt not being able to strip a round off a fully loaded mag.

C4

18

You can certainly trim them down (which is what I do sometimes).

C4

19

I ended up trimming off about one coil in order to get my 10.5 to cooperate.

20

my lmt 10.5 has the standard spring and a h2 buffer and will not run on radway ammo. it has ran through about 2 mags of wolf without issue but that is not enough to say that it is 100% with it. It works 100% with xm193 and the surplus lake city 855. I may try a standard buffer and the radway sometime to see if it makes a difference.