My M3 Compact's Picatinny Rail has manufacture defect. The thickness of both sides are not equal. The right side is obviously thicker than left side, especially the front end. It brought confusion to me in the last two weeks. Finally I found out the problem after switching my MKII's rail. Submitted service form yesterday, now I'm waiting for the response from FX. So if you have hard time to adjust gun cant/scope cant on Impact that with 20 moa rail. Maybe you should check this.