If it doesn't die on the first 75mm AP ping, it's gonna take at least 20 more rounds. (This always seems to be the case for me)
Depends on how you go for it; I've had some fun on the Mindanao map at, IIRC, A25 by driving south to the lip of the second dropoff, overlooking the vehicle spawn point from V69 when attempts are made to use vehicles to support an attack on the field. Because my shells are dropping in on their targets, I can get one- or two-shot disablements fairly easily at ranges out to 2000 yards or so once I've got the range sighted in.
At shorter ranges, picking your target point becomes more important. A couple days ago, I was defending a town when an Ostwind popped up at the nearby spawn point. At a range of about 800 yards, my first round killed his turret, but he maneuvered to put himself bow-on to me, and I bounced two rounds off the front face of the upper hull (where the driver's vision block is, the thickest armor on the vehicle). I changed my point of aim and pumped one round into his starboard running gear, and he tilted over, slewed around, and stopped, bailing about two seconds later.
