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.

No.40A mount

Fits:
BSA Monarch medium action .222, .243 and .308 calibers, front
BSA CF2 and Monarch long action 7mm, .270 and .30-06 calibers, front
Churchill Highlander, front
Colt Sauer, front or rear
Enfield receiver cut down, front
H&R 317 and 322, front
Herters U9 BSA action, front
Interarms Howa, front
Mossberg 1500 and 1700, front
Raptor Arms, front
Remington 700 and 78 long action, front
Remington 725, front
Remington 700 muzzleloader, front
Sauer 200, front
Shilen round receiver, front
S&W 1500, 1600 and 1700, front
Weatherby Vanguard, front

Note:
This is only a single mount. You will need to order two mounts for mounting a scope.