Smith & Wesson K Frame Model 12 Strain Screw Square Butt Blue Steel .38 Special - Part# K128
$9.99
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Smith & Wesson K Frame Model 12 Strain Screw Square Butt Blue Steel .38 Special - Part# K128
$9.99
Smith & Wesson K Frame Model 12 Strain Screw – Square Butt | Blue Steel | .38 Special
Part# K128 | Used OEM Factory Part | Old Style
Part Details
- Part: Strain Screw – Square Butt
- Finish: Blue Steel
- Caliber: .38 Special
- Frame: K Frame
- Style: Old Style
- Condition: Used – Original Smith & Wesson Factory Part
- Installation: Gunsmith fitting/installation recommended
Model Compatibility Chart
| Model | Frame | Caliber | Compatible |
|---|---|---|---|
| Model 12 (Airweight) | K Frame | .38 Special | ✅ Yes – Square Butt |
| Model 10 | K Frame | .38 Special | ⚠️ Verify butt style |
| Model 64 | K Frame | .38 Special | ⚠️ Verify butt style |
| Model 13 | K Frame | .357 Magnum | ⚠️ Verify butt style |
| Model 65 | K Frame | .357 Magnum | ⚠️ Verify butt style |
Note: This is a Square Butt configuration. Round Butt K Frame models require a different strain screw. Always verify your model's butt style before ordering.
How to Identify Your Smith & Wesson Model Number
Swing out the cylinder and check behind the yoke on the frame for the model number. Model numbers began in 1957–58. If there is no model number, your revolver may pre-date 1957. In that case, contact us with your serial number and we'll help identify the correct part.
About This Part
This is a genuine Smith & Wesson factory replacement strain screw manufactured to original specifications and tolerances. The strain screw controls mainspring tension and directly affects trigger pull weight — a critical component for reliable ignition and smooth double-action performance.
Questions? Call or email us — we're happy to help confirm fitment before you order.