Is there some way of determining barrel shank size on a commercial Mauser action without removing the barrel from the action? I have a Type B Sporter with what appears to be a factory installed claw scope mount. The front base is dovetailed into the receiver ring.

I believe the Mauser factory used large ring small shank actions when they made such an installation and I would like to determine if this is the case with my rifle without having to disassemble it to satisfy my curiosity.