Yeah, but it does it worse than a stock T0 mg. It's not fine at all, it's a total waste.
It does not do it worse. To damage or kill a light vehicle with a machine gun you need to bait it in. You can't activate AP round while you are moving and enemies have plenty of time to dodge the attack if you are using the MG offensively. Your AP round will then go on cooldown and you will have to fall back.
Meanwhile, you can A-move the M42 light AT gun with your units and deter enemy light vehicles quite easily.
The M42 light AT-gun is fine. It does what it is supposed to do and that is the following: Provide light AT support to T1 builds.
@Katitof
Does a ZIS3 kill tanks better? Yes. Obviously. But if you tech both T1 and T2 to counter enemy light vehicles then you give away the initiative and mapcontrol to your opponent as you now have invested lots of manpower and time into getting AT.