NPM,
Again, on the Browning BSS, the caps are not slotted on the finished gun, they are engraved with the usual patterns. The new factory threaded caps come overlength with slots. Once the cap is secured, the overlength is milled/filed off leaving no slot to remove it. If it has to be removed, I would simply TIG a piece of square bar onto the cap face and wind it out, then replace it with a new cap.