An early Lyman 57 peep sight, made between 1939-1961. This tang-sight was made especially to fit the M1 and M2 Rifle, the 1903 Springfield,, Mauser rifles, Enfield, Ariska, Sako and Browning rifles.. This tang sight is complete and fits into the two attachment holes on the left flat-receiver side. The sight was designed to provide a high line of sight in proper relation to the comb of these rifle stocks. The line of sight on this tang sight is similar to that of a telescopic sight. The 57 has a quick detachable feature. The standard screw eyepiece is 0.625 inches in diameter, with a 0.040-inch aperature.
