Doug Kibbey photo.

The M1C and M1D were sniper versions of the M1Garand. The two models differed only in the telescope mounts. The M1C mounted a model M81 2.5X telescope; the M1D an M82 2.5X telescope. Both models were used as sniper rifles during World War II, Korea, and during the early years of the Vietnam war. Although considered obsolete, the M1D remained the official U.S. Army sniper rifle until the mid-1960s. Both versions used the standard Army .30-06 cartridge loaded manually, or in eight-round clips. The XM21 [1969] was developed jointly by the Army Weapons Command (Rock Island, IL), Combat Development Command (Ft. Benning, GA), and the Limited Warfare Agency (Aberdeen, MD). The XM21 was an accurized M14 National Match (NM) semi-automatic rifle equipped with a Leatherwood 3X-9X Adjustable Ranging Telescope (ART). The Rock Island Arsenal converted 1,435 M14NM rifles to XM21 sniper rifles for initial fielding to Vietnam in 1969. The rifle was initially fielded with a hardwood stock, which was later replaced with a fiberglass stock. The XM21 was officially type classified M21 in 1975, though it had been informally called the M21 since December 1969. It was the primary Army sniper rifle of the Vietnam war and remained standard until replaced by the bolt-action M24 Sniper Weapon System beginning in 1988. The M21 was accurate to 750 yards (690m). The rifle used U.S. match grade M118 NATO 7.62mm cartridges, in five-round or 20-round magazines. The ART telescope featured a variable magnification power of from 3X to 9X, for adjustable ranging between 300m and 900m. This adjustable ranging feature removed much of the guesswork from aiming at the target. The ART was ballisticly matched with U.S. M118 NATO ammunition (1,800).