To optimize accuracy Henry Scope Mounts are available for all Henry H004 series Golden Boy H006 series Big Boy and H005 Mini Bolt models. Each of these rifles now come drilled and tapped for easy scope mount installation. Our H001 series lever action rifles do not require use of these mounts as the receivers have a 3/8th inch groove to accommodate scope rings. The Golden Boy and 1st generation Big Boy rifles are drilled and tapped under the rear sight. Current production (2nd generation) Big Boys are drilled and tapped on the top of the receiver. To determine which generation of Big Boy you have refer to the serial number table provided so you select the correct mount. Instructions on installation of the scope mounts is provided in the packaging. All Henry Scope Mounts accept Weaver style detachable 1 top mount rings (rings not included).