The MST-100 and MST-150 were developed in the mid seventies by John Unertl in Mars, Pennsylvania for the USMC. These scopes were primarily built for the M40A1 .308 rifle, but were later also made for the .50BMG. Durability was a primary goal, so the complete scope housing and knobs were made from 1018 steel. The elevation knob was design with an integral BDC for the M118LR ammunition, the veneer ring below the main knob adjusts for 1/2MOA deviation from the BDC setting.
When U.S. Optics received the refurbishment contract in 2000, the aging scopes were rebuilt to a higher standard than the originals. With the incorporation of the M40A3 rifle, the rifle now used a 30MOA base which created problems with the elevation and windage adjustments. U.S. Optics removed the two leaf springs and replaced them with a tapered coil spring to allow for perfect tracking. The scopes were also recoated with a durable Teflon coating to keep them from rusting during use. The original wire MIL-Dot reticle was replaced with a recoil resistant type that would survive the recoil created by the .50cal.
Since the MST-100 and 150 were never offered to the general public, the demand for these scopes was very high. U.S. Optics decided to make a limited run of these scopes for the public with great success, so we have now decided to make another run of 100 only. With new materials and CNC technology, the new scope is a precise optical tool capable of competing with the best scopes on the market.
