I recently picked up a 640-3 as part of a trade deal. It has good timing, but had a little too much endshake, about .004 which I think is way too loose for a .357.
I corrected the endshake with endshake washers and after that the B/C gap measured .010 and the headspace was .063.
I noticed that the extractor was below the rear of the cylinder and wondered what would happen if I put the endshake washers under the extractor instead of under the crane. Well I tried it and now the extractor is flush with the rear of the cylinder, B/C gap is .006 and headspace is .067, still in spec.
Now I need to ask the experts, is this a valid fix? Does anyone else do this or should I put the washers back under the crane and live with the large B/C gap?