The mounts that have worked best for me place the center of the optic 2"-2.5" above the center of the bore. Larue is hard to beat. I use their QR mounts for both Aimpoint Micro and Accupoint 1-4. Your stock shape/position will of course play a part in overall satisfaction.
mike r
Don't wish it were easier Wish you were better
Stab them in the taint, you can't put a tourniquet on that. Craig Douglas ECQC
From the several responses it seems that a low mount is preferred.
When the gun transfers to me I will check to see how far fore or aft my Leupold VX-I 1-4 wants to be on the receiver, and look for low mounts that will work. As I recall, this scope needs a fair amount of eye relief, and the charging handle should be far behind the ocular.
Bushmaster 1313, w/ the rail you can use a 1 piece offset mount which allows you a lot of options for perfect eye relief even w/ your fixed A2 stock. Enjoy your new rifle.
mike r
Don't wish it were easier Wish you were better
Stab them in the taint, you can't put a tourniquet on that. Craig Douglas ECQC