I put a strips from an aluminum can in the hook as shims to measure thickness. They came out round, it looks like the wear is on the hook. I used a micrometer on the shims and a feeler gage on the face/breech they checked out at .012. I swore I would never shim. But given such a close tolerance, I believe the shim will give a more precise fit then either turning the pin or welding.

How did you attach your shim to the hook?