Hi all,

Just posting a quick range report from an upper I built. Upper is:
Vltor MUR-1A
Larue 12" stealth w/M4 ramps
Superlative Arms carbine length, solid
Geissele 9.5" MK8 rail

Upper went together with no issues. I just indexed the gas block set screws with the dimples already on the barrel and the op rod seemed to be aligned fine, it spun easily. Frankly I would have been pretty concerned otherwise. I left the gas bleed-off at 3.5 turns out from fully closed. Figured I'd see how that went.

I fired the upper today just to test for function. Started with Centurian M193. Fired one round. Brass landed at 4pm, BCG was fully closed. Hmmm, ok. Pulled the trigger again. Bang. Brass landed at 4pm. BCG was closed. Fired the other three rounds in the mag, bolt locked back on the last one. Pile of brass at 4:00pm. I was almost disappointed that I didn't even have to adjust the gas level! Basically it was boringly reliable. I fired about 30 rounds of M193 and 20 PMC bronze and the thing behaved itself 100%.

Just for kicks, I turned the gas down another full turn and fired one round. The round ejected but the BCG didn't lock back so I opened it up another half turn and all was fine again. That was with the PMC which is a little weak so I left it alone knowing the M193 is hotter.

Dunno what else to say. I'll see how it does over the long run but this was super easy to build and, so far, runs perfectly. Having the BCG and the whole upper receiver be essentially still clean after shooting is just terrific.

-Stooxie

Have any pictures?

Here you go. My strange mix of black, FDE and foliage green. I hunt with my ARs so that tends to be the pattern I use.

I took a picture of the gas block under the rail as well. I was happy to see plenty of room on all sides.

-Stooxie

The first one lined up, obviously, but the second one kinda lined up and I didn't, frankly, give a shit that it wasn't perfect. The SA gas block spacing is 0.500 (LaRue is .450) , so the second dimple was about half exposed. I used a little bit of Rockset on the first dimple, tightened it down firmly, but not too much, and did the same on the second. I'm getting better control of my OCD as I get older. 

But seriously, the first set screw sinks nicely into the deep dimple that LaRue provides so there's no sheer force in the world that's going to move that. I tightened the second one down enough so that's it's pressing against the barrel but not so much that it's going to leave a nasty mark.

-Stooxie