The foundry we work with holds .005" per inch of casting. So if the casting is 5" long they get .025" of tolerance, 2" wide would be .010 of tolerance. Usually they are closer. I don't know if that is an industry standard or not. It's also possible that a new pattern could have been made over the years that Bud and Jim owned them. Patterns get damaged and wear out too.
Best to measure it and compare with a new one.
Bill