Rollin, Out of all the optics options you will be very happy with Sightmark Scope. This is a nice long range scope. Should be no problem with it holding zero. Clip ejecting will not hit scope. You can mount a scope, but only if you buy a scope mount specific to the M1A1 (either made by Springfield, or an aftermarket mount) or install a rail. As delivered, most models do not accommodate a scope.

Rolin, I have a Sightmark Scope, (not this specific model) and have been using it on my Anderson 308 Hunter for 3 years. I have over 1500rds and no function or loss of zero issues. I also favor Primary Arms 4-14x40 ACSS Retical Scope. Maybe Buds will allow us to post pictures someday.