[MattyC]

There is definitely a natural variance in cuts from those years-- and there are also definitely trimmers out there who take advantage of that fact.

But bottom line, the factory was not producing perfect, consistent cuts back in the 50s-- heck, even 70s stuff comes fresh out of the pack or vending box with size variances. If it's egregiously short, easy to stay away. But if it's in the good zone it's often hard if not impossible to tell.