Just purchased redfield esd red dot sight from natchez. Need help with mount. Sight has 30mm tube and looks some what like an aimpoint. Rifle is a colt a3 with bushmaster flip-up rear a-2 sight. Wanting a co-witness set-up. Sog armory has an aimpiont cantilever mount for $69.00. Has anyone tried one? Any suggestions would be helpful.