Smith & Wesson K Frame Strain Screw Stainless Steel Square Butt - 64172C
$5.99
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Smith & Wesson K Frame Strain Screw Stainless Steel Square Butt - 64172C
$5.99
Smith & Wesson K Frame Strain Screw – Stainless Steel, Square Butt
This factory original Smith & Wesson K Frame Strain Screw is a stainless steel mainspring retention screw that secures the mainspring (hammer spring) to the grip frame. The strain screw directly influences trigger pull weight — tightening increases spring tension for more reliable ignition, while backing it out slightly can reduce trigger pull for competition use. This is a genuine OEM replacement for square butt K Frame revolvers.
Part Details
- Part Number: 64172C
- Manufacturer: Smith & Wesson
- Frame: K Frame (Medium Frame)
- Grip Frame: Square Butt
- Material: Stainless Steel
- Function: Mainspring / Hammer Spring Retention
- Condition: Used – Factory Original
Model Compatibility
| Model | Caliber | Type | Compatible |
|---|---|---|---|
| 10, 12 | .38 Special | Centerfire | ✓ Yes (Square Butt) |
| 13 | .357 Magnum | Centerfire | ✓ Yes (Square Butt) |
| 14, 15 | .38 Special | Centerfire | ✓ Yes (Square Butt) |
| 16 | .32 Long | Centerfire | ✓ Yes (Square Butt) |
| 17, K22 | .22 LR | Rimfire | ✓ Yes (Square Butt) |
| 18 | .22 LR | Rimfire | ✓ Yes (Square Butt) |
| 19 | .357 Magnum | Centerfire | ✓ Yes (Square Butt) |
| 48 | .22 Magnum | Rimfire | ✓ Yes (Square Butt) |
| 53 | .22 Jet | Centerfire | ✓ Yes (Square Butt) |
| 64, 64-3 | .38 Special | Centerfire | ✓ Yes (Square Butt) |
| 65 | .357 Magnum | Centerfire | ✓ Yes (Square Butt) |
| 66 | .357 Magnum | Centerfire | ✓ Yes (Square Butt) |
| 67 | .38 Special | Centerfire | ✓ Yes (Square Butt) |
| 617 | .22 LR | Rimfire | ✓ Yes (Square Butt) |
| 648 | .22 Magnum | Rimfire | ✓ Yes (Square Butt) |
| K Frame Round Butt models | Various | Various | ✗ Verify – Round butt may differ |
⚠️ Fits square butt K Frame grip frames only. Verify your grip frame configuration before ordering. The strain screw is interchangeable across both centerfire and rimfire K Frame square butt models.
Usage Note
The strain screw is one of the simplest trigger tuning adjustments available on S&W revolvers. Back it out 1–2 turns to reduce trigger pull weight for target or competition use. Always ensure reliable primer ignition before carrying or using for self-defense.