Strike Industries AR10 Flat Wire Spring, 17-7 stainless steel. A recoil spring for AR-10/.308 platforms. The SI Flatwire Spring is designed to improve cycling longevity, smooth operation, and longevity versus standard springs. It increases bolt load while reducing compression force for more reliable cycling. Model AR-10, Material 17-7 Stainless Steel, Finish Stainless Steel. SKU ACC-STRK-AR10FWS. Manufacturer Strike Industries. Mfg. Part Number AR10FWS. UPC 708747545791. In stock.