So I built an AR-15 and an AR-10 with JP Rifles’ components on Turnbull case hardened steel receivers. The AR-15 is dimensioned milspec and I got it to run like a top and shoot 55gr Armscor ammo into a single hole at 50 yards, so far. Not so with the AR-10 that wears an extra high Picatinny rail. I have tried two scope setups, a USO MST-100 in 30mm steel Badger Ordnance rings with an inch insert, and a Schmidt & Bender 3-12x50 PM II in 34mm steel Badger Ordnance rings. Each runs out of windage adjustments before I can align the point of aim with the point of impact at 50 yards. All optics are mounted on the upper receiver rail. The rifle runs fine otherwise.
I am conjecturing two possibilities:
How can I measure these alignments?
- The axis of the barrel threads is misaligned with the axis of the bolt carrier;
- The axis of the Picatinny rail runs in a plane different from that of the axis of the barrel.