Leupold steel Quick Release (QR) rings and bases make it easy to remove your optic from your firearm and replace it, all while maintaining zero (+/- 1/4 MOA). This specific model is for a Browning BAR and are a popular choice for muzzle loaders and large caliber rifles. The QR mounting system uses a patented lever mechanism, machined with precision tolerances, that engages the steel base to the ring by pulling it down and forward, locking it into place. This easy-to-use system allows you to use multiple scopes on one rifle, making it a great choice for hunters and shooters who travel by air and wish to remove their scope from their firearm. Our QR 1-piece and 2-piece bases accept all QR rings and provide you with the convenience and field-proven accuracy you expect from a mount.