Automatik guns underwhelming?

Hey people,

I am playing metro exodus right now on hardcore difficulty and I have a bit of a rough time until it clicked for me how to play the game (played the last two Metros on normal difficulty with survivor on). But on thing I don't really is the automatic guns. The bastard and the ak seem pretty weak because all mutants just eat them without a problem when not shot in the head. Is it normal like that or am I doing something wrong?

Btw. Happy Eastern ;)