Jim, I heard the same at one time about the old 325s. No reason why the hook and recoil lug couldn't be integral to the bottom barrel. In fact, I don't see why a monoblock couldn't also have integral lumps machined from the solid on the Rolex Oyster principle. Don't think demi-lumps would have any reason to be found on an o/u unless it was one of those side-swing openers.

jack