Pershing tank. The M3 fired an M82 APC shot with a muzzle velocity of . However, both the muzzle velocity of the standard M3 gun and the quality of the steel used in the M82 APC (armor-piercing capped) shot, while comparable to the 8.8 cm KwK 36 L/56 mounted on the Tiger I, were inferior to the Tiger II's KwK 43 L/71 8.8 cm main gun firing its standard APCBC (armor-piercing capped ballistic cap) shot used by German forces, with the result that the former's penetration fell far short of the standard projectile fired by that German tank. As a result, US ordnance provided some T26/M26 tank crews with the 90 mm HVAP (high-velocity, armor-piercing) tungsten penetrator sub-caliber projectile with a muzzle velocity of , or the T33 AP with a re-heat-treated projectile with ballistic windshield and a muzzle velocity of . The HVAP could compete with the KwK 43's penetration performance when firing standard APCBC, but tungsten ammunition was always in short supply. Performance An unsuccessful anti-tank variant was the T8 gun on the T5 carriage. The gun was an M1 with the recoil mechanism from the M2A1 105 mm howitzer. Eventually a version of the T8 with the T20E1 gun and T15 carriage was tested; this led to the 105 mm anti-tank gun T8. Because the standard fifteen-and-a-half foot long M3 90 mm main tank gun proved incapable of penetrating the heaviest frontal armor of the heaviest German tanks such as the Tiger II tank and the rarer Jagdtiger tank destroyer variant, a number of improved versions of the M3 were developed, including the T14 which included a standard muzzle brake and the T15 series. The 90 mm T15E1 L/73, with its long barrel, was designed and developed as an AT gun that could match or surpass the performance of the 8.8 cm KwK43 L/71 cannon, the famous long 88 on the Tiger II. High-velocity 90 mm gun T15 performance The T15 90 mm L/73 anti-tank gun utilized many types of armor piercing ammunition. T43 APBC: A solid shot, it was a modified T33 for use by the T15. It had a muzzle velocity of and therefore increased penetration capabilities. It could punch through of armor angled at 60°(from vertical) up to about . T41 APCBC: Modified M82 projectile of the M3 cannon, fired at a much higher velocity of 3,200 ft/s, than the normal 2,670 ft/s. It