The BX-15 Magnum magazine incorporates technologies that have made the .22 LR BX-15 and BX-25 magazines famous and also features the same feed lip geometry that has proven reliable in the 9-round, JMX-1 rotary magazine. The stainless steel feed lips and "constant force" spring combine with a high-lubricity, polyacetal, anti-tilt follower and durable, glass-filled nylon magazine body to make the BX-15 magazine rugged, reliable and easy to clean. The BX-15 Magnum is compatible with the Ruger Precision Rimfire chambered in .17 HMR and .22 WMR, Ruger 77/17, Ruger 77/22 and Ruger American Rimfire rifles chambered in .17 HMR and .22 WMR. Specifications and Features: Caliber: 17 HMR,22WMR Capacity: 15 Finish: Black Model: 77 Series Material: Polymer Type: Detachable Model Fit: 77/17, 77/22, Precision Brand Fit: Ruger Capacity: 15