Hm, I did some more work on tank MG loadouts using the same formula, but slightly modified
Official Ammo Load 6000 rounds (based on M4 Sherman official loadout)
+50% Ammo Load (Simulates people carrying extra ammo) 9000 rounds
Weapons of Vehicle using Same Calibre (tank MGs) 3
Ammo Load Per Weapon 3000 rounds
Rate of Fire (effective) for the Weapon 300 RPM
Rate of Fire in Rounds Per Second for the Weapon 5 RPS
Ammunition Expended per Action 75 rounds
Shots for Weapon 120 shots
So yeah, the tank MG loadouts are actually quite accurate!