In the WWI airwar, wasn't it considered bad show to fire machineguns with incendiary bullets, designed for taking down ballons by bursting them into flames, into enemy aircraft with pilots? I think there was even a rule saying, that if all your gun had was incendiary bullets, you couldn't fire back at an enemy plane, even if he was attacking you. I guess it was because it was even more painful to have a bullet burning your insides as an added cruelty.
In WWII, didn't they stop following this rule? As I understand, a lot of WWII planes used incendiary bullets?
Edit: I found the bullet I was thinking of was the Pomeroy Bullet. They didn't use them in WWII. It sounded like the Browning .50 caliber could use incendiary bullets, and the British Browning .30 caliber, and didn't the German MG 131 use them too?
Well, since it was WWII, something had to get worse, and the planes were also tougher to shoot down.
The Pomeroy Bullet
Updated - Saturday, 9 August, 2003
The Pomeroy Bullet was an explosive machine gun bullet deployed specifically for use against the Zeppelin threat over Britain. The incendiary bullet, developed by New Zealand engineer John Pomeroy (1873-1950) in 1902, was quickly adopted by British defence services as a means of combating the growing German Zeppelin threat in the skies above Britain.
Filled with nitro-glycerine the bullet ignited the hydrogen gas which escaped from the tear in the Zeppelin gas bag created by the bullet's passage. The bullet's effectiveness led to a marked decrease in the number of Zeppelin attacks.
In time Pomeroy was paid some £25,000 in royalties for his invention
First World War.com - Encyclopedia - The Pomeroy Bullet