Re: GEW 88 bolt head issue
Sorry, I had to edit my first post as I looked at the pic the wrong way.
It the lug on the bolt head is lined up with the slot in the bolt body (it can go only one way if the firing pin is lined up right, the bolt head should just slip right in. Is the bolt head you call the original by chance from one of the "Turkish" rifles. The Turks sometimes made parts for those rifles, and that bolt head looks almost "home made", not the smooth workmanship normally seen. The slot for the ejector looks like it is drilled in a sort of figure 8, not the straight slot I would expect to see, and the ejector itself looks crude and poorly made.
What I am saying is that I think your "original" bolt head is not original, so there might not be the interchangeability you would expect.