Weaver Top Mount Base #46M Matte Black Each base is machined to tight tolerances for a custom fit. Aluminum bases offer maximum strength for rings to hold tight Use as FRONT BASE on: - Browning BBR L/A, S/A - Savage 110-116 L/A series, 210 shotgun (use X-High rings); 10-16 S/A series, Accutrigger models 110-116 L/A, 10-16 S/A - Winchester 52+ (with same hole spacing front and rear), 70 long and short action, 670, 770p Use as REAR BASE on - Savage Accutrigger models 110-116 L/A, 10-16 S/A - Winchester 52+ (with same hole spacing front and rear) May require bolt and/or safety alteration