Why are the cannons so weak on the 109-E, yet so strong on the Russian planes?

[winny]

Calibre doesn't have an awful lot to do with the comparison. You'd have to know the weight of projectile, % of High explosive per round (if any), muzzle velocity and Rounds per second. Assuming that all of that is accuratley portrayed...

For example the early 109's had 2 wing mounted cannons and 2 nose mounted MGs with 60 rounds of ammo for each gun and fired 520 rpm, the british initially went with 6 or 4 .303 MGs with 300 rounds of ammo for each gun and double the rpm of the german guns, however a 3 second burst from the german gun weighed 8 kg (and exploded on contact) and a 3 second burst from the british only delivered just under 6kg and didn't explode on contact. They started fitting cannons to spitfires in July '40 and the Hurricanes got 4 cannons from '41 onwards.

I don't know enough about Russian guns to say if they are correct but I do know that they were all very efficient. It could be right.

The most destructive cannons used in WWII were the ones fitted to the Me-262, try a training mission in it and see if it brings down a B-17 easily...