I bought an 89 Norinco SKS the other day. It came with a bipod mounted in the same hole the bayonet uses to pivot on. The screw that was in the hole was the one that came with the bipod, not the one that came with the carbine. I ordered a replacement bayonet off eBay because it was cheap and came with the screw I (thought I) needed. So, I put the screw in and lo and behold, there are no threads to hold it in. It fits perfectly, it just doesn't have anything to screw into.
To be more specific, the bayonet lug has two holes, one on either side. The hole on the left side (looking down the barrel from the rear) is counter-sunk so the head of the screw fits flush. It does and looks factory. The right side is just a hole and the screw fits perfectly to the end, it just doesn't have anything to thread into.
Can anyone PLEASE tell me what I need to do? This is driving me nuts to figure out!
It sounds like someone drilled out the threads in the lug.
Maybe you can replace it with a screw similar to what colt uses for a front take down pin.