The experimental round , called the T48 , used a concentrated incendiary compound .
The experimental round , called the T48 , had a muzzle velocity of 3,400 feet ( 1,000 m ) per second , which was 20 % greater than existing ammunition .
The experimental round , called the T48 , used a concentrated incendiary compound and had a muzzle velocity of 3,400 feet ( 1,000 m ) per second , which was 20 % greater than existing ammunition .