I recently tore apart my LMT upper with the Troy MRF-R rail, ER Shaw 7.62x39 barrel, Model 1 Sales Bolt, enhanced firing pin, and Smith Vortex 9mm SMG Flash Hider (1/2x36tpi). I am building a 7.62x39 pistol with intentions of making my LMT lower a registered SBR. The pistol is the easy way of getting the bugs out of the upper before I spend an extra 2 Benjamins on getting a 2x2 stamp…
So, I took the upper apart.
Heavy barrel profile…
I had purchased a cardinal forge upper locally for $60. I checked for M4 feedramps----GTG. The finish was less than ideal, but I’m going to use this for a cheap plinker and possible light game hunter this season so no reason to get a Mega billet or something to that effect. I just wanted function.
Inserted barrel, torqued the barrel nut to 50ft-lbs, saw that my gas tube would line up perfectly, and pinned the gas block back on. It did look like this originally.
You’ll note the brass shims in the barrel nut pocket of the Troy rail. This is due to the fact that to keep it from rotating on the barrel nut I had to tighten the allen-head screws down to where the rail would sit about 1/16" under the height of the upper. Trying to be innovative I got some sheet brass and cut some little spacers/shims. In doing so I could regulate how much pressure it took to get the rail to not rotate and keep the same height as the upper. I did have to put one under the gas tube as well to account for the diffrence otherwise the rail would be pointing up at the muzzle end. I did find that you can get them nearly dead-nuts and keep the same level all the way across.
Once finding the rail in line with the upper I put the charging handle and BCG back into the upper. Liberally applying CLP to the interior of the upper and barrel prior putting the CH and BCG is something I always do.
Here’s the finished (yeah right) gun. Scope is a Leupold Rifleman 4-12x40 in a 1-pc cantilever mount. Nice and clear, and with the mount I can get any amount of eye relief that I want with the adjustble stock. I did use a 6.5 Grendel magazine loaded with 20rds of 7.62x39 and it fed each round perfectly. I like the look better than the 7.62x39 CProd mags anyway. It looks normal…
I hope anyone looking into building an upper can find inspiration here. I love doing this and once you do your first upper you’ll not likely want to buy another complete upper ever again. I certain don’t, and like how I can customize any of my ARs to exactly how I want them. Thanks for looking and God bless.