LMT MRP 12" SBR $1899.00 or a home built AA 8.5" SBR $700.00?

Wife and I own these.  I got the LMT and love it, we go mag for mag when we go shooting and I've always looked at her Adams Arms when she's on the line and thought "lol, okay."  As I tightly clung to my precious LMT.  Don't get me wrong, she wanted a weapon she could paint any color without ruining any intrinsic value, so I used premium parts, PSA CHF CL 8.5" bbl, AA carbine kit, Spikes upper, LMT CH, Colt Defender 2000 complete lower, samson rail, magpul SL furniture.  Like I said, great parts, no doubt, but I never looked at it seriously.  Until after this last range trip.  After cleaning, during really, I noticed an awful divot in the LMT upper, that was not present in the AA upper...

Neither weapon has had a single issue, ever, the LMT even cycled on a round that was so weak it sounded like a 9mm went off.  I removed the round from the chamber, checked the bore, not hearing the PING on the steel target and an odd recoil impulse I assumed the worse yet it was clear.

Now the LMT cycles quite a bit more roughly than the AA by hand, and my ego has been dented.

Make up your own minds.  Adams Arms has really impressed me.


LMT




The cam pin appears to be digging a trench in case the Jerry's come over the horizon.


Adams Arms




Here's a couple of the BCG just because it still looks new.  I might actually have to buy one of AA's glock slides or barrels now....



LMT if you're out there, is this okay?  Is this normal?  I've got a lot of DI AR's with way more rounds down range, often needing a BCG before the upper receiver started showing wear like this...

If you're not, I'll send over an email referencing this post.

I've had POF roller cam pins in my piston guns since day one.

Zero wear showing anywhere

This is normal for a piston guns since there is no gas to unlock the bolt. Go with a roller cam.

I have the same experience as well with the POF roller cam. I have 3 factory POF rifles that all came with roller cams from the factory. I also installed the roller cam kits on my Colt LE6920 and Sig M400 when both were new. All five rifles show zero wear from the cam pin.

OP, I would get ahold of LMT and see if they will warranty the upper receiver for you. It appears to be pretty torn up from the photos. If so, also get yourself a POF roller cam and you'll be good to go. The POF roller cam is a cheap upgrade and I highly recommend them based on my own experiences.

The carrier is what locks/unlocks the bolt. It doesn't really matter how you move the carrier- gas, piston, or manually.

That amount of wear is not indicative of the finely tuned machine it should be.
Quite a few things can cause that, so if they do do anything other than tell you it is normal, they will want the whole thing back.
Slot not cut to rotate the bolt enough, that surface in the upper a bit fat, head on the cam pin fat, lots of things.

POF roller cam pin... always made sense, never had a problem..
(first use years ago was a 1000 round training course, no issues all day or since and almost no wear)

Would removing the gas rings on the bolt eliminate the cam wear?

IIRC, in the M27 thread they mentioned early designs having issues digging a hole in the side of the upper from the cam pin there.  The fix was to make the factory cutout in the upper for the cam pin larger.

My BumpSAW put a fairly deep gouge in the upper so I swapped a roller cam pin in.  Not sure if it's really making a difference, but I figured it wouldn't hurt. Worst case the roller cam pin breaks and I'm out a few dollars.  It spends most it's time at almost 1,000RPM and I believe the high carrier speed is a contributing factor.

Not really.

If you don't go with a roller, polish the forward corner of the cam pin head to a nice smooth radius, instead of the angle cut.  It doesn't have to be a big radius, .010" to .015" will do.