Made from 7075 aluminum alloy, the rail has a black, hard-coat anodized finish. It is attached to the receiver using five high strength, 410 stainless steel, 8-36 screws. The overall length of the screws is 0.375 inches. The screws have conical heads (82° included angle) that engage conical bores within the rails thus establishing an over-constrained condition which effectively prevents any movement between the rail and the receiver. Additionally, the underside of the rail engages the cylindrical body of the receiver in a manner that effectively, and redundantly, prevents yaw. This solution ensures reliability, scope mounting choices, and economy.
To choose the rail angle that will make available most of the elevation adjustment within the scope, you need to determine how much elevation adjustment the scope has, divide that number by two, and then subtract either 15 MOA or 4.4 milliradians. 15 MOA (or 4.4 mils) is subtracted because approximately 6 MOA (1.7 mils) must be allocated to obtaining a 100 yard (or 100 m) zero, assuming the scope is mounted approximately 2” (50mm) above the bore. In addition, approximately 9 MOA (2.6 mils) must be allocated for build tolerances of the rifle, the scope mount, and the scope. This is an approximation, but it is more than adequate for choosing the rail angle. In general, 20 MOA (5.8 mils) is appropriate for scopes having 30mm tube diameters, and 30 MOA (8.7 mils) is appropriate for scopes having 34mm tubes.