Originally manufactured by the Unertl Optic Company as a 10x USMC 7.62x51 mm NATO calibrated optic, this scope is one of a limited number converted for the U.S. Marine Corps to .50 BMG calibration for use with M82A1/M107 semi-automatic sniper/anti material rifles. The left side of the adjustment body is marked "USMC" over the serial number "1521", with the original ".30 CAL" marking milled away and replaced with ".50 CAL". As a part of the conversion, the elevation knob was replaced by Unertl with a .50 BMG calibrated knob graduated from 100 to 1,800 yards. Fitted with a pair of "GGG" marked scope rings. Includes a matching numbered Civilian Marksmanship Program (CMP) certificate of authenticity dated January 24, 2019.

Exceptionally fine overall as converted to .50 BMG by Unertl, issued by the U.S. Marine corps, and subsequently surplussed through the CMP, retaining 90% plus black finish with some minor edge wear, a few minor dents on the bell, some minor flaking on the windage turret, clear adjustment markings, and a few minor handling marks. The optics are clear with a crisp reticle. Overall a very attractive example of a .50 BMG converted USMC Unertl 10x scope with less handling wear than what is typically expected from an issued optic.