{"product_id":"smith-wesson-k-frame-strain-screw-square-butt-models-17-18-173c","title":"Smith \u0026 Wesson K Frame Strain Screw - Models 17 \u0026 18 - Square Butt - Blue Steel - Old Style - Used - .22 LR 173C","description":"\u003cp\u003e\u003cstrong\u003eFactory OEM Smith \u0026amp; Wesson K Frame Strain Screw\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePart Number:\u003c\/strong\u003e 173C\u003cbr\u003e\u003cstrong\u003eCompatibility:\u003c\/strong\u003e K Frame Models 17 \u0026amp; 18\u003cbr\u003e\u003cstrong\u003eCaliber:\u003c\/strong\u003e .22 LR (Rimfire)\u003cbr\u003e\u003cstrong\u003eGrip Type:\u003c\/strong\u003e Square Butt\u003cbr\u003e\u003cstrong\u003eFinish:\u003c\/strong\u003e Blue Steel\u003cbr\u003e\u003cstrong\u003eStyle:\u003c\/strong\u003e Old Style\u003cbr\u003e\u003cstrong\u003eCondition:\u003c\/strong\u003e Used\u003cbr\u003e\u003cstrong\u003eFrame Size:\u003c\/strong\u003e K Frame\u003c\/p\u003e\n\u003cp\u003eThis is an authentic Smith \u0026amp; Wesson factory strain screw (also called a mainspring tension screw) for K Frame Models 17 and 18 revolvers with square butt grips. The strain screw adjusts the tension on the mainspring, which controls hammer fall and trigger pull weight.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFeatures:\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eGenuine Smith \u0026amp; Wesson factory part\u003c\/li\u003e\n\u003cli\u003eBlue steel finish matches original factory specifications\u003c\/li\u003e\n\u003cli\u003eSquare butt configuration\u003c\/li\u003e\n\u003cli\u003eOld-style design for early production models\u003c\/li\u003e\n\u003cli\u003eUsed condition with functional threads\u003c\/li\u003e\n\u003cli\u003eDirect replacement for damaged or missing strain screws\u003c\/li\u003e\n\u003cli\u003eAllows adjustment of mainspring tension\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eCompatibility Note:\u003c\/strong\u003e Strain screws are interchangeable across all K Frame models with the same grip frame style (square butt vs round butt). This square butt strain screw will fit Models 10, 12, 13, 14, 15, 16, 17, 18, 19, 48, 64, 65, 66, 67, 617, and 648 that have square butt grip frames. It will NOT fit round butt models.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunction:\u003c\/strong\u003e The strain screw threads into the bottom of the grip frame and applies tension to the mainspring. Tightening the screw increases mainspring tension (heavier trigger pull, harder hammer fall), while loosening it decreases tension (lighter trigger pull, softer hammer fall). Proper adjustment is critical for reliable ignition.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eInstallation:\u003c\/strong\u003e The strain screw can be installed by the owner. However, proper adjustment requires knowledge of safe mainspring tension levels. Too little tension can cause light strikes and misfires; too much tension creates excessive trigger pull weight. Professional gunsmith adjustment recommended for optimal performance.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow to Identify Your Smith \u0026amp; Wesson Model:\u003c\/strong\u003e Swing out the cylinder and check behind the yoke on the frame for the model number. Model numbers began in 1957-58. If you need assistance identifying your revolver or confirming compatibility, contact us with your serial number.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eQuestions?\u003c\/strong\u003e Contact us at \u003ca href=\"mailto:sales@usagunsandgear.com\"\u003esales@usagunsandgear.com\u003c\/a\u003e or call 770-544-8075. We specialize in Smith \u0026amp; Wesson pistol and revolver parts - new, used, NOS, and refurbished.\u003c\/p\u003e","brand":"Smith \u0026 Wesson","offers":[{"title":"Default Title","offer_id":39638857973818,"sku":"173C","price":6.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1423\/2020\/products\/DSC00981_bb48a36b-090c-4051-9618-86a22d2780eb.jpg?v=1656605159","url":"https:\/\/usagunsandgear.com\/products\/smith-wesson-k-frame-strain-screw-square-butt-models-17-18-173c","provider":"USA Guns And Gear","version":"1.0","type":"link"}