A little barrel work for a PR

[MD*GSP]

Hoping someone will look over my shoulder on this one and, perhaps tell me how to deal with a problem.

Awhile back I acquired a new-to-me 20ga P-Repro that I am liking quite a bit. The gun feels very lively and balanced in my hands beyond any other 20ga PR I’ve handled. I am fortunate enough to have a set of original PR 16ga barrels. With said barrels in place, the gun is just over-the-top nice and feels livelier still. Balance is just right. I didn’t get lucky enough that the 16ga barrels fit the gun to my satisfaction though (of course). Although I would have preferred to work the barrel hook to get the barrels fit to the frame just right, the ill-fit is in the opposite direction. With the barrels installed, the join of the barrel breech and the standing breech is off a bit. There’s a small gap at the lower portion so, theoretically (exaggerated of course), the muzzle is pointing up. Gun locks tight and the lever is about centered favoring the right. I could probably shoot it as is but, nah.

To fix it, I trimmed a pc of .002 steel shim stock but it wasn’t quite there yet so I trimmed a pc of .0015 shim stock to add to it. The action closed fine but the lever was a little far to the right and I could detect just a shade of mismatch at the top of the barrel join to the breech face. Went back to my cache of shim stock and carefully cut a pc of .003 steel shim stock. I cut it accurately so that it occupies the whole of the space between the water table. I also cut it long enough so that the entire bearing surface of the hook about its circumference maintains full contact. A little squeeze in a precision vise to flatten any curled edges followed by a wrap around a gage pin to get it curled proper before laying it in. Followed up with a dab of grease to hold it in place and, it lays atop the pin beautifully. The barrel join at the standing breech is now perfect. The barrel flats are lying perfectly along the water table and, there is a small gap at the ninety-degree flat / breech face junction. Perfect but for one thing. The rib extension (dolls head) stands proud atop the frame by about .015 - that’s alot. Although it’ll be fine for the upcoming season, I would like to final correct it so the barrels are perfectly fit beyond function.

How does one go about correcting the proud rib extension?

In the off-season I will find (or make) a roll joint that is .006 larger than the one that is installed in the gun as it sets now. That will eliminate the shim. Then I’ll refit the 20ga barrel set by cutting the hook back by .0015 on the Bridgeport and then creep into final fit by hand so it’s perfect and, tight.

To the experts, I'm not going to have to grind the barrel flats to get the rib extension flush top-side, am I?

Am I blinded and just not seeing another way to do it?