NOTICE to owners of GMRB’s “Drop-In” barrels: There is a possibility that the nipple on your rifle is defective. Metric threads were installed on some barrels in place of the proper ¼-28 threads for nipples. These barrels, if affected, will have a serial number between #030672 and #031352. If you have a barrel in this serial range and doubt the nipple threads please call Morgan at 603-447-1095 or email mbowden@gmriflebarrel.com to arrange a return, inspection and repair if required. We apologize for any inconvenience. Thank you for your support.