This is a must have for pcc conversion! - Stern Defense AR-15 10 inch Assembled Upper Receiver, 8.5 in 9mm Barrel w/MLOK Rail

I purchased the 8.5" upper and a Stern Glock mag adapter together. Check out my review of the adapter elsewhere. The two combined resulted in one the coolest, most fun shooting AR-style platform I've ever owned. The build of upper was tight. Every part torqued just right with no looseness or gaps anywhere. There was practically no seam between the upper and my random, no name AR lower. The finish was smooth without any discernible flaws in the paint/coating. The M-LOK handguard was finished very nicely with no razor sharp edges that you get from cheaply made Asian handguards (you know what I'm talking about) and the picatinny rails lined up perfectly with the upper. I disliked the cuts on the handguard until I realized they are a bunch of "S" for Stern Defense then I thought "okay, that's pretty slick". Charging handle is perfect for one handed racking. Bolt carrier rides very smooth with none of the grittiness you feel with with cheaper bolt carriers. I tested the build with about 400 rounds of UMC and S&B 115 gr FMJ, and 20 rds of Federal JHP at 50 yards on a steel plate. Using a 1.5X ACOG, the gun produced NO MISSES. Even walking up on the plate from 15 to 5 yards in rapid fire (semi-auto...private range) the gun was really controllable with barely any flip. Recoil felt like a 5.56, just lighter. So no slower or faster, just lighter. Mag changes with the adapter was slick, almost as fast as a standard AR tac reload. I also thought the muzzle blast can was chunky and looked like an afterthought until I started shooting it. It does a great job directing the noise and blast forward, helping make the gun more controllable. Although, I will probably switch it to something sexier later. Only complaint is how dirty the bolt and adapter got when I opened it up. Make sure you keep it clean! Otherwise, fat kudos to a very well built product!