A sighting device, usually a disk or segment with a central peephole, so designed to fit in the breech end of the gun tube for the purpose of aligning the sights with the gun.
NSN 6650-00-445-6990
NSN 6240-00-954-0124
NSN 6145-00-110-4127
NSN 5895-00-908-7444
NSN 5998-00-951-6466
NSN 2925-01-448-2880
NSN 5910-01-029-0871
NSN 6610-01-527-8006
NSN 5915-01-329-9545
NSN 6320-01-411-9222
NSN 5855-01-152-8782
NSN 5895-00-772-9386