I just picked up a No. 1 frame 12g. GH S/N 70,756.
28" Damascus Barrels. Fishtail top lever. Needs a buttstock. Broken off at the wrist (will get that fixed

) but all else on the gun is very nice.
Anyway... I also have this No. 1 frame P grade with Vickers barrels on it that is a bit earlier (in the 60,000's range) than the new GH.
I figured for kicks to see how the GH barrels fit on the PH or if they fit at all.
To my surprise, they go right on, lock up tight and have perfect fit in every way around the action. Like they were make for the gun.
The Vickers barrels from the PH also go onto the GH. But the barrel lug is a but snug on those.
Neat.