I just picked up a used Bulgarian AKS-74. Overall, I found a few things about the rifle that were goobered up. I fixed most of those.

The folder however is quite loose. Once unlatched, the stock swings freely with virtually zero resistance. My Tula AKS-74U (fresh build) is nice and snug.

Any suggestions on how to tighten this up? Could the builder have used a 4.5mm pin instead of 5.5? Is it just wear? Suggestions?

Thanks!

There is no way to tighten it. I have 3, 2 fold back and forth very easily and 1 does not. They are supposed to fold back and forth with no effort.

Take a couple spent .22 cases. Cut off ends and then cut down the sides. Insert in hinges and then insert pin.
See how that works for you.

Not a bad idea, might have to try that.