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19mm Becker Cannon

By Brian Clark

19mm Becker Cannon Dimensions
also known as the 20mm Becker Cannon




Bullet diameter



Rim diameter



Base diameter



Case mouth diameter



Case Length



20mm Becker Cannon Case and projectile

I found this cartridge at a Washington Arms Collectors show a couple of years ago. I initially thought it was the result of idle hands and imagination. I was wrong. After a little digging in my library, I found a nice article by Ian V. Hogg (Encyclopedia of Firearms, 1987, page 82).This article shed a little light on the true heritage of the cartridge. The case seemed to be a 20mm Oerlikon cartridge case cut down. I was close. It turns out that the 20mm Oerlikon cartridge was based on the 19mm Becker Cannon cartridge. Check the rebated rim and rounded web of the case base. The key for me was the headstamp. It has an August 1916 date. The 20mm Oerlikon cartridge was not introduced until about 1930 so it couldn’t be a cut down 20mm Oerlikon case.

The following is a little information drawn from Ian V. Hoggs’ article.

The 19mm Becker Cannon cartridge was developed in 1916 by two German brothers by the name of Conders. The Conders brothers were employed by the Stahlwerke Becker of Reinickendorf, Germany. The cannon was an automatic weapon of blowback design and used a differential locking system. The 19mm Becker Cannon cartridge used a high explosive projectile with a contact detonator. The cannon had a 15 round vertical feed magazine and could be fired either in single shot mode or in a fully automatic 300 rounds per minute mode.

It was reported that the Germans used the 19mm Becker Cannon as an anti-aircraft gun with some used on Gotha bombers. It is believed that there was less than 400 cannons manufactured.

After the end of the First World War the Stahlwerke Becker company was not allowed to manufacture any firearms. To remain in business, they sold their patent rights to a Swiss company, Maschinenbau AG of Seebach. Maschinenbau AG made some modifications to the basic design of the cannon and marketed it as the Semag-Becker Cannon for use as an infantry support weapon. This marketing was not successful and the company went into receivership in 1924. The patents, weapons, staff and machinery were acquired by the Oerlikon Machine Tool Company of Switzerland. The cartridge was redesigned to a use a 20mm diameter projectile and the case was significantly lengthened. This redesigned case became the famous 20mm Oerlikon cartridge.

The case is brass with a Berdan primer 0.430 inches in diameter. The projectile is hollow and turned from steel with a bronze driving band and a lead alloy nose with a spring loaded contact fuse or detonator. This can be seen in the image detail of the nose piece. Why was there a hole crosswise completely through the nose? I am assuming it was for an insert to ‘safe’ the cartridge during handling. Note the pin extending into the hole. The cap is spring loaded and when pressed, the pin extends through the crosswise hole and into the body of the head detonating the projectile. Can anyone add to this?

20mm Becker Cannon projectile and contact detonator

Below are the case headstamp drawing and image and the bullet base.

20mm Becker Cannon headstamp drawing20mm Becker Cannon headstamp and projectile base.

If anyone has any information about the manufacturer of the cartridge as seen on the headstamp or has a photo of the Becker Cannon, could you please send them to us so we can post it here with credits.
Please contact us at Armory Publications with your response.

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