Smith & Wesson J Frame Mainspring Stirrup MIM Hammer Factory New OEM - 215860000

Smith & Wesson J Frame Mainspring Stirrup — MIM Hammer, Factory New OEM

Part #215860000 | Factory New | J Frame | MIM Hammer Models | Multi-Caliber | OEM

⚠️ MIM Hammer Models Only. This stirrup is designed for J Frame revolvers fitted with MIM (Metal Injection Molded) hammers, which S&W transitioned to beginning around 1997. The MIM hammer has a different stirrup engagement geometry than pre-MIM (forged/machined) hammers. Installing this stirrup in a pre-MIM J Frame will result in improper fit, light primer strikes, or failure to fire. Verify your hammer type before ordering.

The mainspring stirrup is the U-shaped link that connects the mainspring to the hammer, transmitting the mainspring’s stored energy to drive the hammer forward during the firing cycle. A worn, bent, or broken stirrup causes light primer strikes, inconsistent trigger pull weight, or complete failure to fire.

Compatible Models (MIM Hammer Variants)

• .22 LR: Model 317, 43C
• .22 WMR: Model 351C
• .32 H&R Mag: Model 331, 332, 431, 432
• .38 Special: Model 337, 342, 438, 442, 637, 638, 642
• .357 Magnum / AirLite: Model 340, 360
• Verify fitment: Model 60, 49 — confirm MIM hammer configuration with your gunsmith before ordering

Specifications

• Part Number: 215860000
• Type: Mainspring Stirrup
• Frame: J Frame
• Compatibility: MIM Hammer models only (post-~1997 production)
• Condition: Factory New
• OEM: Genuine Smith & Wesson factory part

Installation

Professional gunsmith installation recommended. Verify MIM hammer compatibility and function test trigger pull and primer strike depth after installation.