{"product_id":"sw-k-frame-strain-screw-stainless-square-butt-64172c","title":"Smith \u0026 Wesson K Frame Strain Screw Stainless Steel Square Butt - 64172C","description":"\u003ch2\u003eSmith \u0026amp; Wesson K Frame Strain Screw – Stainless Steel, Square Butt\u003c\/h2\u003e\u003cp\u003eThis factory original \u003cstrong\u003eSmith \u0026amp; Wesson K Frame Strain Screw\u003c\/strong\u003e 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.\u003c\/p\u003e\u003ch3\u003ePart Details\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e 64172C\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Smith \u0026amp; Wesson\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFrame:\u003c\/strong\u003e K Frame (Medium Frame)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGrip Frame:\u003c\/strong\u003e Square Butt\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Stainless Steel\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFunction:\u003c\/strong\u003e Mainspring \/ Hammer Spring Retention\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCondition:\u003c\/strong\u003e Used – Factory Original\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eModel Compatibility\u003c\/h3\u003e\u003ctable\u003e\n\u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eModel\u003c\/th\u003e\n\u003cth\u003eCaliber\u003c\/th\u003e\n\u003cth\u003eType\u003c\/th\u003e\n\u003cth\u003eCompatible\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e10, 12\u003c\/td\u003e\n\u003ctd\u003e.38 Special\u003c\/td\u003e\n\u003ctd\u003eCenterfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e13\u003c\/td\u003e\n\u003ctd\u003e.357 Magnum\u003c\/td\u003e\n\u003ctd\u003eCenterfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e14, 15\u003c\/td\u003e\n\u003ctd\u003e.38 Special\u003c\/td\u003e\n\u003ctd\u003eCenterfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e16\u003c\/td\u003e\n\u003ctd\u003e.32 Long\u003c\/td\u003e\n\u003ctd\u003eCenterfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e17, K22\u003c\/td\u003e\n\u003ctd\u003e.22 LR\u003c\/td\u003e\n\u003ctd\u003eRimfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e18\u003c\/td\u003e\n\u003ctd\u003e.22 LR\u003c\/td\u003e\n\u003ctd\u003eRimfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e19\u003c\/td\u003e\n\u003ctd\u003e.357 Magnum\u003c\/td\u003e\n\u003ctd\u003eCenterfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e48\u003c\/td\u003e\n\u003ctd\u003e.22 Magnum\u003c\/td\u003e\n\u003ctd\u003eRimfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e53\u003c\/td\u003e\n\u003ctd\u003e.22 Jet\u003c\/td\u003e\n\u003ctd\u003eCenterfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e64, 64-3\u003c\/td\u003e\n\u003ctd\u003e.38 Special\u003c\/td\u003e\n\u003ctd\u003eCenterfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e65\u003c\/td\u003e\n\u003ctd\u003e.357 Magnum\u003c\/td\u003e\n\u003ctd\u003eCenterfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e66\u003c\/td\u003e\n\u003ctd\u003e.357 Magnum\u003c\/td\u003e\n\u003ctd\u003eCenterfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e67\u003c\/td\u003e\n\u003ctd\u003e.38 Special\u003c\/td\u003e\n\u003ctd\u003eCenterfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e617\u003c\/td\u003e\n\u003ctd\u003e.22 LR\u003c\/td\u003e\n\u003ctd\u003eRimfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e648\u003c\/td\u003e\n\u003ctd\u003e.22 Magnum\u003c\/td\u003e\n\u003ctd\u003eRimfire\u003c\/td\u003e\n\u003ctd\u003e✓ Yes (Square Butt)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eK Frame Round Butt models\u003c\/td\u003e\n\u003ctd\u003eVarious\u003c\/td\u003e\n\u003ctd\u003eVarious\u003c\/td\u003e\n\u003ctd\u003e✗ Verify – Round butt may differ\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\u003cp\u003e\u003cem\u003e⚠️ Fits \u003cstrong\u003esquare butt\u003c\/strong\u003e 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.\u003c\/em\u003e\u003c\/p\u003e\u003ch3\u003eUsage Note\u003c\/h3\u003e\u003cp\u003eThe strain screw is one of the simplest trigger tuning adjustments available on S\u0026amp;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.\u003c\/p\u003e","brand":"Smith \u0026 Wesson","offers":[{"title":"Default Title","offer_id":41251789373498,"sku":"64172C","price":5.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1423\/2020\/files\/DSC00431.jpg?v=1771433377","url":"https:\/\/usagunsandgear.com\/products\/sw-k-frame-strain-screw-stainless-square-butt-64172c","provider":"USA Guns And Gear","version":"1.0","type":"link"}