CNC Machined from solid Billet 7075 Aluminum. If you want to build a high end UltraMatch Upper, look no further than the Rainier Arms UltraMatch Billet Upper.
The most critical features are:
* Parallelism between the picatinny rail, main center bore and the centerline of the mounting lugs
* Perpendicularity between the centerline of the lugs and the barrel mating face (at the front of the threads)
* Flatness of the barrel mating face
We are holding .0003 or better on all of those measurements. Competitor uppers are between .001 and .003 on the perpendicularity and parallelism.
* A3 Flat-Top
* A4 Flat-Top - w/M4 Feedramps