I have a new LMT and it has problems. My gunsmith has corrected many problems, but one remains. Loading any mag with 15 or more rds (ten or less no problem) results in a FTF with the FIRST round - most times failing to be completely extracted from the magazine. The bolt lugs move the round forward about 1.5 inches then jam the round before it loads into the chamber and I have to drop the magazine with one hand while pulling back the charging handle with the other. This happens only on the first round and does not happen otherwise. The bolt stays open on the last round. I tried a little experiment with using a lot of Slip 2000 on the bolt and carrier and it worked but there is something holding up the carrier while charging. I am getting ware marks on the top left part of the charging handle too. Lastly, this bolt carrier group has about 400 rounds fired through it from the first upper that I returned to LMT because the barrel was over tightened and shooting left. The returned upper did not have this problem of FTF. Anything I should look for at the range prior to going back to my gunsmith would be appreciated. Thanks.

sounds like a bad mag. did you try different mags?
how are the feed lips on the mag?
ETA: I re read the post. only at 15 or more rounds in the mag? still sounds like bad feed lips
what kind of mag is it?

I don't think it is the weapon.

Need to know what is stopping the bolt/carrier/bullet.

Is the tip of the bullet striking below the feed ramps on the receiver?
Is the firing pin collar catching on the hammer on the forward stroke?
Is the Key just binding up in the charging handle track, and this is causing the charging problem?

It is not the mags. I have tried 5-6 diffrent ones to include HK SA80s, OKAY, & Cooper (Perban age) all new. The gunsmith had to polish up the chamber area as LMT left the steel burrs and they were scratching the bullets. Some quality control. LMT offered to exchange the gun for a new one but I already spent money on this one. They now load nice and they sound correct. Just like my Colt.I think something is slowing up the bolt coming forward. i will check out DANO 523 suggestions and get back ASAP. Thanks.

Just checking.  Are you hitting the bolt release, or riding the charging handle?

Quoted: Just checking.  Are you hitting the bolt release, or riding the charging handle?

Damn we think alike, first thought I had too.

I hit the bolt relese as the empty mag locks back the bolt.  Again a lot of Slip 2000 makes the problem go away for a time. Something is holding it up and I will play around with it this evening and post what I find. Thanks,

PS. the place I got this set up returned 15 complete rifles and 40 uppers to LMT. They were told LMT fired the QC guy also.

Is your buffer and buffer tube lubed up?

I had the exact same problem, but I never tried it with less than 15 rounds.  Sent the upper back to the vendor, who sent it back to LMT.  The new one is smooth as butter.  I haven't been able to shoot it yet, but I can ride the charging handle forward until it contacts the round, let it go, and 1 push on the FA, in it goes.  Even smoother than my Colt.  

ETA:  I was using a Colt CAR stock with an H-buffer.

OK I went to the range today with the LMT all greased up. Worked well but did have one jam/FTF. The HK mag was loaded to 30 and the first round had the bolt  move it forward (on charging) and then it boged down prior to entering the chamber. Tip was not in contact with anything and the lugd made dents in the case and scratch on the bullet itself. So now I have something to take to the gun smith and ask them WTF Over? I think if it was not over greased it would have jammed more. When the thing loads it works through the entire mag with out problems. Lastly I know I am not the only LMT owner with this problem. If you know others ask them to post here too. Thanks

UPDATE

I got the rifle back from LMT and it works better. They said they could not find anything wrong but did put in a heavy buffer and things worked fine for them. Also said they only had problems with my HK Mags. A little confusing. Today I had two interesting FTFs and they may explain the original problem. The first one just was a result of the bolt passing over the round. The second moved the round and deposited it under the bolt prior to traveling up the feed ramps. But when I droped the mag the bolt did not move. It was sort of stuck in place until I repositioned my hands and then it closed. Some thing is rubbing against the bolt carrier assembly. When I get some quiet time this week I will take it apart and try to see whats up. Any recommendations as to what to look for would be appreciated. Thanks  

Yes. I can ask a friend to me let use his and see what we get. The bolt carrier slides real nice when open with no scraping. This has been a real learning experience for me. I fired an M16 for the first time  in BCT/B33/ Ft Dix in 1969.  That one worked better than this one. Go figure.

I'm thinking your gas key might crooked and rubbing on the inside of the charging handle. Make sure that puppy is lined up right.

Other questions, is this a complete LMT? Lower, upper, bolt carrier group, etc? Is it a 14.5" or a 16"? Are you using the enhanced bolt or a standard one?

Rusty & M4 ARC, I think you guys are close on this and will look deeper into your suggestions. I got around today of swaping my lower with a buds Armilite lower. My upper worked like a champ on his lower. On my LMT I believe the bolt carrier is dragging on the hammer as I see a small bright scratch on one side of the top of the hammer. Some of the other things you mention may be part of the problem too but we are now in an area that is beyond my ability to fix. At least I can show my smith some marks in the gun. The gun is an LMT 16 inch with the standard bolt carrier group. When firing it and holding the trigger after a round goes out I get a loud snap and a feel just like it gives in a function test. Lastly, the gas rings always were w little hard when puting the bolt back in the carrier. Do not know if this is of any concern? It still is a blast to shoot but I want to get it right. Any recommendations from you folks iare much appreciated.

What style carrier and hammer?