{"product_id":"sw-k-frame-model-12-strain-screw-square-butt-blue-steel-38-special-k128","title":"Smith \u0026 Wesson K Frame Model 12 Strain Screw Square Butt Blue Steel .38 Special - Part# K128","description":"\u003ch2\u003eSmith \u0026amp; Wesson K Frame Model 12 Strain Screw – Square Butt | Blue Steel | .38 Special\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003ePart# K128 | Used OEM Factory Part | Old Style\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003ch3\u003ePart Details\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePart:\u003c\/strong\u003e Strain Screw – Square Butt\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFinish:\u003c\/strong\u003e Blue Steel\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCaliber:\u003c\/strong\u003e .38 Special\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFrame:\u003c\/strong\u003e K Frame\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eStyle:\u003c\/strong\u003e Old Style\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCondition:\u003c\/strong\u003e Used – Original Smith \u0026amp; Wesson Factory Part\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eInstallation:\u003c\/strong\u003e Gunsmith fitting\/installation recommended\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eModel Compatibility Chart\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003cthead\u003e\n    \u003ctr\u003e\n      \u003cth\u003eModel\u003c\/th\u003e\n      \u003cth\u003eFrame\u003c\/th\u003e\n      \u003cth\u003eCaliber\u003c\/th\u003e\n      \u003cth\u003eCompatible\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003ctd\u003eModel 12 (Airweight)\u003c\/td\u003e\n\u003ctd\u003eK Frame\u003c\/td\u003e\n\u003ctd\u003e.38 Special\u003c\/td\u003e\n\u003ctd\u003e✅ Yes – Square Butt\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eModel 10\u003c\/td\u003e\n\u003ctd\u003eK Frame\u003c\/td\u003e\n\u003ctd\u003e.38 Special\u003c\/td\u003e\n\u003ctd\u003e⚠️ Verify butt style\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eModel 64\u003c\/td\u003e\n\u003ctd\u003eK Frame\u003c\/td\u003e\n\u003ctd\u003e.38 Special\u003c\/td\u003e\n\u003ctd\u003e⚠️ Verify butt style\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eModel 13\u003c\/td\u003e\n\u003ctd\u003eK Frame\u003c\/td\u003e\n\u003ctd\u003e.357 Magnum\u003c\/td\u003e\n\u003ctd\u003e⚠️ Verify butt style\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eModel 65\u003c\/td\u003e\n\u003ctd\u003eK Frame\u003c\/td\u003e\n\u003ctd\u003e.357 Magnum\u003c\/td\u003e\n\u003ctd\u003e⚠️ Verify butt style\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e\u003cem\u003eNote: 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.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch3\u003eHow to Identify Your Smith \u0026amp; Wesson Model Number\u003c\/h3\u003e\n\u003cp\u003eSwing 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, \u003cstrong\u003econtact us with your serial number\u003c\/strong\u003e and we'll help identify the correct part.\u003c\/p\u003e\n\n\u003ch3\u003eAbout This Part\u003c\/h3\u003e\n\u003cp\u003eThis is a genuine Smith \u0026amp; 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.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQuestions?\u003c\/strong\u003e Call or email us — we're happy to help confirm fitment before you order.\u003c\/p\u003e","brand":"Smith \u0026 Wesson","offers":[{"title":"Default Title","offer_id":40932774936634,"sku":"K128","price":9.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1423\/2020\/files\/s-l960_38_d494ab19-0eb9-4d72-9e13-4431592f66ff.webp?v=1751913753","url":"https:\/\/usagunsandgear.com\/products\/sw-k-frame-model-12-strain-screw-square-butt-blue-steel-38-special-k128","provider":"USA Guns And Gear","version":"1.0","type":"link"}