I ordered a combo set with a slick side upper. I received it today and I was thrilled with the quality of the parts. I plan to cerakote mine, but I wanted to function-check everything before I send it off to cerakote. Everything on the lower functioned flawlessly with, and without, the upper installed. My only gripe (and its kind of a big one) is that none of the 6 handguards I have will fit this upper. The front of the upper is flared out to prevent the use of any handguard that has 'alignment' tabs that would normally rest either side of the upper, just under the pic rails. I planned to build a .300 BLK pistol with this set. I had a 9.3 inch barrel and an 8.5 inch handguard already waiting for this combo set. I bought hose specifically so that my supressor would mount flush with the handguard. Now my only options are to use a different upper, buy a JL Billet 8" angled handguard and either deal with the half-inch gap and the slash-cut look, or buy a shorter barrel and hope the suppressor fits inside far enough to hide the slash-cut. Not very happy with any of these options right now and I may just try to sell this combo set to buy one that will work with the other parts I already bought. Never thought this set wouldn't work. It's a great set. The quality is great. Receiver fit is great. Finish is great (even though I'll be cerakoting it). It just won't work with any of the handguards I have.

Unsure if I can call it numero uno, but it did impress a world class machinist/‘smith (ZRTS) in Indiana., who btw, sells fantastic billet lowers.

This is a slick side billet upper and is NOT mil-spec meaning many handguards will not fit this upper without extensive modifications due to the flared body behind the barrel nut threads. It fits the JL Billet lower but fairly sure these are extruded and then milled instead of being forged. This won't hurt the average user but it is not as strong as a forged billet receiver (yes such a thing exists). JL Billet appears to want you to buy only their lower and hand guard for the best fit. I ordered mine raw and it appears to be bead blasted but the JL Billet lowers I received are not. I wish there was more consistency in the finish from JL Billet, my lowers needed a lot of work to be usable as they appeared to be rushed during production. These fit very loose on my JL Billet lowers.

fits my Spikes tactical lower. slightly a different color and there is a step from the lower down to the upper. havnt fired it yet. We shall see.