The Salvo Squeeze Bore (SSB) is a system designed to increase hit probability and/or target saturation. This objective is attained through firing a number of projectiles with each shot through a barrel of special squeeze design. The projectiles are nested in tandem array in a conventional cartridge case and separate as they pass through the barrel. Frankford Arsenal ordered 2,000 rounds from Colt in early 1973 for a Personal Defence Weapon (PDW) evaluation on a M1911 fitted with a special barrel. There were three 55gr. bullets that were stacked in a white plastic sabot. The tests showed some promise with consistent patterns at 50 feet, but pressure was a problem and further tests did not continue. (Erlmeier, Brandt Ref. 440A)