S&W J Frame Model 642-2 Airweight Hammer (MIM) .38 Special +P – Part# 642G

Smith & Wesson J Frame Model 642-2 Airweight Hammer (MIM) – Stainless Steel

Restore reliable ignition on your Model 642-2 Airweight with this factory-original MIM hammer. The hammer is the primary firing component — it falls under mainspring pressure to strike the transfer bar and firing pin, igniting the primer. On the 642-2, the internal hammer is concealed within the frame (hammerless design), making it double-action only and snag-free for concealed carry. A worn, chipped, or damaged hammer causes light strikes, misfires, or complete failure to fire. This MIM (Metal Injection Molded) stainless steel hammer is the correct factory replacement for the J Frame Model 642-2 chambered in .38 S&W Special +P.

• Part Number: 642G
• Fits: Smith & Wesson J Frame Model 642-2 Airweight
• Caliber: .38 S&W Special +P
• Part Type: Hammer (Internal / Concealed)
• Material: MIM (Metal Injection Molded)
• Finish: Stainless Steel
• Condition: Used (factory original)
• Installation: Professional gunsmith fitting required – hammer timing and transfer bar engagement are critical safety functions

About MIM Parts

Metal Injection Molding (MIM) is a precision manufacturing process used by Smith & Wesson and other major firearms manufacturers to produce complex internal components with tight tolerances and consistent quality. MIM parts are genuine factory components — not aftermarket substitutes — and meet the same specifications as traditionally machined parts.

Factory Replacement Quality

Genuine Smith & Wesson factory part manufactured to the exact specifications and tolerances of the original — same dimensions, same transfer bar engagement geometry, same reliable ignition. No aftermarket substitutes.

Finding Your Model Number

Swing out the cylinder and check behind the yoke on the frame. Model numbers have been stamped there since 1957–58. If your revolver has no model number, it predates that era — contact us with the serial number and we'll help identify the correct part.

Questions? Call or email us — we're happy to help you get the right part the first time.