This is a question I've occasionally wondered.
How does a tank-mounted mg compare with its infantry-versions ?
The MG 34 in, say, a Pz III. Is is comparable to a MG 34 in an lmg role or is it closer to a HMG ? I'd suppose an lmg, but I'm not sure. You don't get the "firepower" rating of tank-mounted mg's anywhere.
I suppose a tank with 3 mgs (such as a Stuart) would be more effective than one with only one ?