Let's talk K Gun serial numbers

Let

Obviously the serial number of the receiver on a Krieghoff defines when it was manufactured. Apparently 5 digit serial number goes up to the late 80's (?) and thereafter serial numbers are six digit.

The question becomes, other than the fact the receiver is older and could be more likely to need repair, is there a reason to be suspicious of older receivers ? I've often heard there is reason not to purchase a Model 32 Krieghoff below serial number 4500 or so as the metal is "softer."

I am trying to find an excellent condition used K80 and have been shied away from a couple of lower serial numbered guns. I'm sure there is not much that can't be fixed on a receiver including having the "ears" welded due to wear from shooting thousands of rounds. I just don't want to buy someone else's problem(s). Other than relying on the reputation/veracity of the seller and checking with Ottsville - any general concerns re: older vs newer ?