Initially designated as the T28E1 Combination Gun Motor Carriage ( CGMC ) , it was accepted into service in 1943 as the M15 .
The M15 evolved from the T28 project , an outgrowth of a 37 millimeter ( 1.5 in ) gun mounted on a M2 Halftrack .
Initially designated as the T28E1 Combination Gun Motor Carriage ( M15 ) , M15 was accepted into service in 1943 as the M15 .
The M15 evolved from the T28 project , an outgrowth of a 37 millimeter ( 1.5 in ) gun mounted on a M2 Halftrack .