Nobody makes bases to fit as many guns as Weaver. Yet each base is machined to tight tolerances for a custom fit. They're designed to fight the effects of recoil with a square cut notch that precisely mates to the sturdy cross bolt in every Weaver Detachable Ring. Custom hardened fastening screws come with every Weaver base.

2 of these are required to mount a scope

Fits:
BSA Monarch medium action 222, 243 and 308
BSA CF2 Monarch long action
Churchill Highlander
Enfield receiver cut down
Herters U9 round receiver
Interarms Howa
Mossberg 810 and RM7
Raptor Arms
Remington 700, 721, 725 and 7B long action
Remington 700 muzzleloader
S&W 1500, 1600 and 1700
Weatherby Ultra Lightweight and Vanguard