Actually the performance of the 2cm guns is a mess in this game since the units using them (222, luch, Centaur) use different mechanism for no good reason.
Don't know why you keep bringing this up, there are tons of weapons in the game that have multiple versions or types because the game is only historically flavoured and chooses gameplay over reality. Different mechanisms are used for either variety or different gameplay purposes.
There are three different types of the 88mm L/71 gun, Tommies Bren and UC Bren, 3 different types of MG 42 (with up to 7 different versions), 3 different types of G43, two different versions of the 75mm L/70, almost all standard issue rifles having up to three or more different versions, do I need to go on?