When I found top rib came out on Whitworth fluid steel English made barrels, I unsoldered ribs and found 'tonns' of corrosion flakes under ribs and pinhole just in the middle of right barrel.
Just soldered this pinhole with braze and soldered ribs at the place again.
These barrels shoot still and without any problems, of cause with light loads.
Clair Kofoed knows this story, I told him, when he was here.

Geno.