Bullet Comparison with 20mm, 50 cal, and 40mm

The National WWII Museum EDU

These three calibers of ammunition were the standard low to mid level anti-aircraft defense of US Naval surface vessels. After the vicious kamikaze attacks off of Okinawa in 1945, the Navy deemed the .50 caliber and even the 20MM inadequate in their ability to effectively disintegrate an aircraft intent on crashing into a ship. Navy findings concluded that the 40MM was the smallest caliber weapon capable of destroying the Japanese kamikaze, and had planned to replace most of the shipboard 20MM mounts with the 40MM mounts, however the war ended before the navy executed this plan.