Quote:
Originally Posted by swiss
It does nothing.
Other than entertain the crew inside with rain-like sound. 
(proven, a relative of mine was a panther driver) |
On most armored vehicles 7.62 mm or similar rounds does nothing, except for AP rounds against very light mild steel armor at close ranges. In a few cases, though, you might get spalling against slightly heavier armor, which might injure crewmen or damage very delicate components. Spalling is unlikely to do any damage to the drive train, engine block or gun, however.
Practically, shooting small caliber bullets at AFV does three things:
1) It allows you to aim your heavier guns. You shoot first with light caliber guns, observe where your bullets fall, then shoot with your heavier weapons - assuming they have roughly the same trajectory or you correct accordingly.
2) It forces AFV to remain "buttoned up" limiting the crew's visibility from inside the vehicle and preventing them from manning top-mounted AAA MG.
3) The rattle of bullets might "rattle" the crew. Inexperienced tank crews might retreat or maneuver defensively, on the assumption that all those bullets are just a precursor to something much worse. In some cases this is a valid assumption, since MG were sometimes used as ranging weapons for AT guns. This result could be built into a "mobility kill" option that makes tanks move defensively.