Bullet types.

[Sogamg]

Hello.
I am playing campaign,normal with Bf-109 F4.
The question I have is this.
The MG17 is good for enemy fighters and the MG151/20 is good for heavier airframes as bombers and attack planes?

This way works for me because with MG17 I only scratch the IL-2s and Pe-2s but with the MG151/20 I can make really a lot of damage.
So is it how it is supposed to work or am I doing something wrong?The MG17 can shoot down an enemy bomber without having to empty your magazine of bullets?

[Guest deleted@1562]

The MG17 is most useful for killing enemy rear gunners and sometimes pilots, too. 

[Sogamg]

So I guess MG17 cannot do sufficient damage to a heavy aircraft,maybe at its engines.

[L3Pl4K]

Use the Mg17 to check your deflection. If the rounds hit, fire also with mg 151.