Forgot to mention that Collath also made an extensive line of shotgun gauge ball cartridges. I not long ago bought a Sauer underlever hammer gun that was a Cape Gun type. The left barrel was a normal 16 ga shotgun and the right barrel was a 20 ga chamber with a rifled barrel the had the groove diameter of 16 bore and the bore diameter of a 20 gauge. I finally realized that they had used a set of 16 gauge rough tubes and bored the left barrel to 16 ga and the right barrel to 20 ga bore and then rifled it to a groove diameter of near 16 ga diameter. The chambers were made to several lengths in each ga and the one I had was made for a 1-5/8" chamber length. One thing this did is yield a barrel with much more barrel thickness than would be present in a shotgun barrel of standard configuration or with a standard Paradox barrel. I tried a couple of cast balls of varying diameter until I found one the pushed through easily and filled the grooves completely.
