No drilling, tapping or major alteration. Guaranteed to hold zero. Can be removed and reinstalled easily. Includes 1" fully machined, horizontally split scope rings and is windage adjustable. Made in the USA of top grade military allan aircraft aluminum.

Installation instructions for M-1A or M-14 

To install your mount, place the side plate on the left of the receiver, with mounting rails engaged into the grooves cut into the receiver. Install the knurled bolt, then install E-clip and lock the side plate into place by tightening the bolt securely. If the bolt does not thread into receiver easily, check receiver thread for burr on outside edge of hole. 

Put the top-plate in place, and tighten the (2) cap screws. Install the scope rings according to instructions found on box. (E-clip goes on backside of the side plate). If 12-32 knurled bolt threads are tight in receiver, use hex key in slot to tighten.