Between 1968 and 1969, S&W shipped 23 (known serial numbers) Model 29-2 revolvers, some frame only, to Aircraft Armaments INC, (AAI), in Cockeysville, MD for conversion to what was known as the Tunnel Gun. After a 3 month field test between July-Oct 1969 in Vietnam, it was renamed the Quiet Special Purpose Weapon (QSPR), after some minor mods were made to the weapon. The changes made were based on recommendations from soldiers from the 25th ID, the 23rd (Americal) ID, and the 1ST ID, who field...