AT apc's ok, that makes sence. Tanks no. WIERD. Well your tank commander is doing his own thing. Nothing to do. If its m60 you 900 .50 cal rounds. Would not worry to much about that. In next beta Andrey fixed issue with .50 cal ammo. It should now kill APC's, and IFV's like the real deal.
Steel Armor: Blaze O War (SABOW)---
ISABOW mod. Check Graviteam forum. New AI vehicle M113a1 with recoiless and M106a1 self propelled mortar carrier. Much of other little stuff too.
Requires AUG SABOW patch from Graviteam. Enjoy