Weaver 401S Top-Mount Aluminum Scope Base, S&W L/K/N

The Weaver 401S is a one-piece top-mount aluminum scope base designed for factory-drilled Smith & Wesson L, K, and N-frame revolvers. Machined to tight tolerances, the base provides a stable Weaver-style platform for scope rings and optics. Constructed from aluminum alloy, it balances strength and weight while delivering a secure attachment point on compatible revolvers. Rings are not included; the base accepts standard Weaver-style rings.

Key Specifications

• The application is specified as S&W REVOLVERS-FACTORY DRILLED.
• The material is listed as ALUM ALLOY.
• The fit is for S&W K/ L/ N Frame revolvers.
• The unit is a 1-piece design.
• The product type is 1-Piece Base.
• The type of rings needed is WEAVER STYLE.
• Rings included: No.
• Dimensions are given as 1.25 X 2.70 X 4.70.
• The listed weight is 0.12 with a shipping weight of 0.1.

Built for a straightforward, secure optic installation on compatible revolvers, the Weaver 401S delivers a machined, one-piece mounting solution that prioritizes fit and repeatable alignment. Its aluminum-alloy construction keeps weight low while providing a solid interface for Weaver-style rings, making it a practical choice for shooters who require a durable, factory-drilled top mount without modification.