Regarding the tank kill debate. You are both right.
A 12.7 MM round, even a SLAP round, will not penetrate a tanks armor. However, you do not need to blow a hole in a tank neutralize it.
For example, knocking out targeting systems, periscopes, or breaking the tread on a tank all help to degrade the ability of said tank to be an effective combat unit. Just rent the movie about the Russian Tank in Afghanistan. A .50 SLAP round can take out key components of the tank if the angle is right.
The problem in OFP is the damage model does not include in detail the various systems on a MBT or IFV. A model that did was in the old Twilight 2000 pen and paper game for all of you old timers.
Regards,
Norelsk