This 40mm U.S. BOFOR Anti-Aircraft round is 17.62 inches long and would weigh 4 3/4 pounds when filled with propellant. The weight of the projectile is 1.985 lbs for a high explosive round and 1.960 lbs for armor piercing. The Muzzle Velocity could reach speeds up to 2,890 feet per second and had a ceiling height of 22,299 feet. At a 40 degrees angle this beast could reach out and touch a target out to 11,208 yards.
The Bofors 40mm gun originated as a German Krupp design back in 1918. The WW 2 40mm was manufactured by the Bofors Company in Sweden which, quite literally hand built and fitted each weapon. Mass production techniques were not used by Bofors. When the United States bought the rights to manufacture the 40mm, we did employ mass production techniques which allowed us to produce the 40mm by the thousands. The British produced the Mark 1 single barrel and the Mark II double barrel. The United States produced single, double and quad mounts of the 40mm and supplied them to all our allies. The 40mm was the Navy's standard intermediate range anti-aircraft weapon throughout WW 2, the Mk IV quad mount being extremely effective. The 40mm was used post-war until fast-moving jet aircraft became commonplace. The rate of fire is 160 rounds per minute per barrel and was clip fed 4 rounds at a time, although some guns could use a 48-round clip. The average life of a barrel was 9500 rounds.
The picture on the right is the headstamp marking on this round.