After doing a lot of experimenting and asking around, I finally found a "traditional" upper receiver that fits the LMT MWS lower. In my search I tried a Larue OBR upper, an Armalite AR10a upper, and the Centurion Arms MK11 upper. Most everyone knows the about the lack of standardization among large frame AR's which leads to serious headaches when trying to get parts to play nicely. My LMT lower is a non MARS type lower.
- The upper / lower fit with the larue OBR upper I tried was probably the best as far as things lining up, but I could not get the takedown pins started. The upper belonged to a friend and I didn't have a chance to gauge the diameter of the takedown pin holes on the upper, but I believe the holes could be reamed out to work. No issues with the function of the lower receiver's controls.
- The Armalite AR10a fit well also, probably as well as the Larue. Problem was the pin holes on the upper were pretty small.... small to the point where it might be even too much material to remove with a reamer, but if one was so inclined, I don't see why you couldn't enlarge the holes. No issues with the function of the lower receiver's controls.
- The Centurion Arms MK11 was the first one I tried and at first I was a little disappointed. The front pivot pin went in tight but the rear one would only go in about a quarter of the way. Centurion Arms claims on their website that these receivers ARE compatible with the LMT MWS lowers so I expected it to drop in, but I guess this is par for the course when dealing with large frame AR's. The upper / lower fit was good, not as good as the above two but still not bad at all.
I couldn't find a stripped Larue upper to modify so I ended up keeping the Centurion MK11. In order to make the rear pin slide in, I used an adjustable reamer to slowly enlarge the hole until the pin would go in. Now it takes a light tap with a wood mallet to seat the rear pin and the upper / lower has no slop whatsoever. I removed very, very little material from the hole. It actually looked like I just cleaned up a burr or some irregularity in the coating that was keeping the pin from going through.
Overall I'm happy... This give MWS owners a pretty good option to stray away from the LMT offerings, not that there is anything wrong with them, but options are nice. This upper will be assembled with a Craddock 18" bartlein, JP LMOS BCG, and SLR handguard. I figure it will be about 1.5 lbs lighter than the equivalent LMT 18" upper which is nice.
PICS:
- The upper / lower fit with the larue OBR upper I tried was probably the best as far as things lining up, but I could not get the takedown pins started. The upper belonged to a friend and I didn't have a chance to gauge the diameter of the takedown pin holes on the upper, but I believe the holes could be reamed out to work. No issues with the function of the lower receiver's controls.
- The Armalite AR10a fit well also, probably as well as the Larue. Problem was the pin holes on the upper were pretty small.... small to the point where it might be even too much material to remove with a reamer, but if one was so inclined, I don't see why you couldn't enlarge the holes. No issues with the function of the lower receiver's controls.
- The Centurion Arms MK11 was the first one I tried and at first I was a little disappointed. The front pivot pin went in tight but the rear one would only go in about a quarter of the way. Centurion Arms claims on their website that these receivers ARE compatible with the LMT MWS lowers so I expected it to drop in, but I guess this is par for the course when dealing with large frame AR's. The upper / lower fit was good, not as good as the above two but still not bad at all.
I couldn't find a stripped Larue upper to modify so I ended up keeping the Centurion MK11. In order to make the rear pin slide in, I used an adjustable reamer to slowly enlarge the hole until the pin would go in. Now it takes a light tap with a wood mallet to seat the rear pin and the upper / lower has no slop whatsoever. I removed very, very little material from the hole. It actually looked like I just cleaned up a burr or some irregularity in the coating that was keeping the pin from going through.
Overall I'm happy... This give MWS owners a pretty good option to stray away from the LMT offerings, not that there is anything wrong with them, but options are nice. This upper will be assembled with a Craddock 18" bartlein, JP LMOS BCG, and SLR handguard. I figure it will be about 1.5 lbs lighter than the equivalent LMT 18" upper which is nice.
PICS:
