LMT upper issue

Gothmog said:
... and no filing necessary, but thanks for the input.

I was looking at your pics and noticed that the firing pin was missing from my pic. I never thought much of it as I regularly run that bolt without a pin for use in a teaching gun, and without any problems.

Now here's the tricky bit ... I always use the lower with the old style hammer in combination with that bolt as a 'trainer'. It appears that the non notched (old style) hammer works happily without a firing pin. The notched hammers do not!

Case closed, I think ....

IMG_3925-1.jpg


Old style hammer ...

IMG_3926-1.jpg


Newer style hammer, notched to prevent slam fires ....
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So there never was an "LMT Upper Issue"... the problem was with the other components you used, which were not LMT products.

Just want to clarify that for others who are reading this THREAD. ;)

Mark
 
Questar said:
So there never was an "LMT Upper Issue"... the problem was with the other components you used, which were not LMT products.

Just want to clarify that for others who are reading this THREAD. ;)

Mark
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More like LACK of other components ;) , but your comments are right on the money as regards the LMT upper ... there does not appear to be any issue with it at all.

I may take it to the range today and give it a real test.
 
mebiuspower said:
Post should've begin with..

"I mixed a LMT upper with a Colt bolt carrier in it and now it's screwed up ..." LOL.
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Why? The Colt carrier had nothing to do with the problem and neither did the mixing of different manufacturer's parts. :confused:

I'll be shooting it with that very same carrier this afternoon.
 
Well, it shoots accurately enough but it's short stroking. I should mention that this upper has a 10" barrel attached.

Time to play with the gas block unless someone has some other ideas. The original FSB has been replaced with a JP gas block and flip up front sight. I thought perhaps that the JP block would work better than some of the stuff I've dealt with before ... I guess we'll see.

The other option is to go back to the original FSB as I have a spare here.
 
Gothmog said:
Well, it shoots accurately enough but it's short stroking. I should mention that this upper has a 10" barrel attached.

Time to play with the gas block unless someone has some other ideas. The original FSB has been replaced with a JP gas block and flip up front sight. I thought perhaps that the JP block would work better than some of the stuff I've dealt with before ... I guess we'll see.

The other option is to go back to the original FSB as I have a spare here.
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10.5" LMT are made to run with 5.56 ammo. What ammo were you running?

Did you try loading one round to see if the bolt locks back?
 
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Leg said:
Uh oh! I think I know the upper you mean. I was looking at it myself, but decided that it was just too good to be true. Especially once the seller started ignoring all my follow up questions. I don't think that the upper is LMT at all. The seller told me it had no markings on either the upper or barrel, not to mention that the FSB has no bayo lug. It's possible that it's a cut down and the gas port would need to be opened up. Remove the flashider, that will tell you if it's cut down or not.
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That would suck if I got an LMT upper that was actually home build unit. :mad:
 
All LMT barrels are marked. the 10.5 barrels are marked behind the gas block. It should be something like 5.56mm MP CB 1/7 something, with the proper government profile

Old LMT uppers are not marked - but you can tell they did not mill out the little area next to the ejection port cover eyelet.

Also, LMT 10.5" will have the M4 feed ramp.
 
Paulinski said:
10.5" LMT are made to run with 5.56 ammo. What ammo were you running?

Did you try loading one round to see if the bolt locks back?
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I used American Eagle 55gr 223 ... I may have some surplus FNM kicking around and will give that a try, although I am doubtful it will make any difference.

With a single round in the chamber and none in the mag the bolt fails to lock back upon firing.
 
greentips said:
All LMT barrels are marked. the 10.5 barrels are marked behind the gas block. It should be something like 5.56mm MP CB 1/7 something, with the proper government profile

Old LMT uppers are not marked - but you can tell they did not mill out the little area next to the ejection port cover eyelet.

Also, LMT 10.5" will have the M4 feed ramp.
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Thanks for the info GT.

I will check this out as I am able to. I am not very technically skilled and have few tools for this kind of work so will need to beg a favour or two locally. Thus getting this upper verified might take me some time ...

When I get home I'll post some pics of the upper and see if anyone here can offer yet more insight into this issue.
 
A few pics

10inupper3-1-1.jpg



10inupper4.jpg


10inUpper2.jpg


10inUpper.jpg


10inupperJPEgasblock.jpg


Evidence of gas leaking at on both sides of JP Ent gas block. The 3 screws on the bottom are quite secure.

I'm not sure how much can be told from these pics, but toss in your wisdom if you have something to offer. I'll begin removing the FH early next week if I can find someone cooperative and skilled. ;)
 
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Gothmog, once you get the upper apart put the original FSB on, adjustable gas blocks cause nothing but problems, I have all the tools to round trip the upper but R33 is borrowing them right now. Wrenchgod has all the bits at Hunter's too. I suspect the short stroking will go away as soon as the OE FSB is back on provided all the parts are real deal LMT. And for GODS sake man, a gun with KAC, Eotech and LaRue on it does not deserve the ridicule that comes from putting a piece of tape on the speed bump.;)
 
sparrow said:
And for GODS sake man, a gun with KAC, Eotech and LaRue on it does not deserve the ridicule that comes from putting a piece of tape on the speed bump.;)
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Wrong kind of tape? How does camo sound? :D

What's the ETA for your tools? :)
 
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