{"product_id":"smith-wesson-k-frame-model-66-strain-screw-square-butt-old-style-357-magnum-used-66172b","title":"Smith \u0026 Wesson K Frame Model 66 Strain Screw Square Butt Old Style .357 Magnum Used - 66172B","description":"\u003ch2\u003eSmith \u0026amp; Wesson K Frame Model 66 Strain Screw — Used OEM Part\u003c\/h2\u003e\n\u003cp\u003eGenuine Smith \u0026amp; Wesson factory strain screw for the K Frame Model 66 revolver, chambered in .357 Magnum. Square butt configuration, old style. Stainless steel. Removed from a used firearm and in good working condition. A direct OEM replacement for a worn, damaged, or missing strain screw.\u003c\/p\u003e\n\u003cp\u003eThe strain screw secures the mainspring (hammer spring) to the grip frame and directly influences trigger pull weight. Tightening increases spring tension for more reliable ignition; backing it out slightly can reduce trigger pull for target or competition use.\u003c\/p\u003e\n\u003ch3\u003ePart Details\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e 66172B\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCondition:\u003c\/strong\u003e Used OEM\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFrame:\u003c\/strong\u003e K Frame\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCompatible Model:\u003c\/strong\u003e Model 66 (.357 Magnum)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGrip Frame:\u003c\/strong\u003e Square Butt\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eStyle:\u003c\/strong\u003e Old Style\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaterial:\u003c\/strong\u003e Stainless Steel\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eCompatibility Note\u003c\/h3\u003e\n\u003cp\u003eThis is the old style strain screw for square butt K Frame Model 66 revolvers. Verify your grip frame configuration before ordering — round butt and square butt strain screws differ, and old and new style are not interchangeable. To find your model number, swing out the cylinder and check the frame behind the yoke.\u003c\/p\u003e\n\u003ch3\u003eInstallation\u003c\/h3\u003e\n\u003cp\u003eStrain screw replacement requires removal of the grip. Installation by a qualified gunsmith is recommended.\u003c\/p\u003e\n\u003cp\u003eQuestions? Call or email us — we carry new, used, and new old stock S\u0026amp;W parts for the full K Frame lineup.\u003c\/p\u003e","brand":"Smith \u0026 Wesson","offers":[{"title":"Default Title","offer_id":40702497292346,"sku":"66172B","price":6.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1423\/2020\/files\/DSC03691.jpg?v=1730476913","url":"https:\/\/usagunsandgear.com\/products\/smith-wesson-k-frame-model-66-strain-screw-square-butt-old-style-357-magnum-used-66172b","provider":"USA Guns And Gear","version":"1.0","type":"link"}