The chamber is really odd with the raised bumps.

I know of people who use old charge bars that have a fixed powder charge. In other words, no bushing. Just a fixed measure usually on an old 1 1/8 oz. shot charge bar. Stuff from the sixties. Those bars will throw a scary amount of a fast powder like Red Dot.

I saw a guy damage an LC Smith doing just that. I told him those charge bars were for paper shells and fiber wads but he insisted the loads were fine. Even after his gun was damaged.