Barrelsmith Mike Orlen of Amherst MASS had a pictorial on here a few yrs. back which included: pix of round bar or transfer punch of suitable diameter which acted as a caul to hold shim in place in the hook, clamping pts. for a simple C-clamp, rec. for solder content and fluxing, wet rags in bore. You've got all that stuff and Capability to boot so go for it. I stuck one in the hook of an Ithaca NID with some nondescript cyanocrylate which wasn't Black Max and it held for a couple yrs. Whatever you put in there, shim or weld metal, will have to be eased and humored with a file, abrasive sleeve, or mill simply because it isn't a simple problem of reducing the diameter of the hook. You're setting the barrels back. If what you need is X dimension at the back of the hook to do so, shimming all the way round the hook reduces diameter by 2X which means the hook will simply wedge on the pin and gun won't close. My shim was feathered too the hook metal top and bottom before it closed.
jack
