The APCR rounds does no damage to tanks with the exception to half-tracks, planes and in some hearsay the backs of tanks.
The rounds are bugged, so I recommend not using them until they are fixed.
No, it’s the same. Seems like Legarhead misunderstood OP since the APCR rounds is the spec that’s meant to increase damage against vehicles. Damage is the same against infantry afaik. Even heard people say APCR makes them do no damage to infantry. Although I can’t confirm that since they worked fine against infantry when I tried them, was only the vehicle part that was bugged.