MG151 cannon and two .50 machine guns. The projectiles themselves are identical to those fired by the NS-37 aircraft cannon. They were attacked by whites armed with rifles, revolvers and a small cannon. It was armed with four 20mm cannon, augmented first with bombs, then rockets. Maximum projectile velocity obtainable with gunpowder in cast cannon was approximately . Police responded to crowds with tear gas, water cannon, and rubber bullets. Those familiar with the sound of cannon fire say the sound is nearly identical. The HVP is capable of being fired out to from a conventional cannon. Donkey Slug&colon; A donkey with a mounted vulcan cannon. A-10s also shot down two Iraqi helicopters with the GAU-8 cannon. Hind helicopter using its 20mm Vulcan cannon. There were sometimes contingents of foreign mercenaries, armed with cannon or handguns. Later models incorporated an M61 Vulcan rotary cannon. Iron production expanded as demand for cannon and munitions was insatiable. The hull was wide with two more cannon in sponsons.