Daryl,

The ball & shot, paradox, explora and other guns designed for single projectile and shot cartridges were chambered for the paper case. This generally came in two forms, the paper case and the paper-lined brass case. The vintage all brass cased ammunition used in these guns had an internal paper lining that reduced the internal dimensions to that of the paper case. The best way to think of the design is a full length - super high brass cartridge. I believe this was done to increase the durability of the cartridge, while still providing a normal chamber for shotshell ammunition.

Many confuse the vintage all brass paradox ammunition with the thin all brass cases used in the larger bored gauge rifles. I have seen paradox loading data for the Magtech brass - wrong choice...

The correct case our Ball & Shot guns is the current plastic or paper case. Ross and Sherman favor the Federal paper hull for the 12 ga. There are zero issues in chambering a Federal paper loaded with a seated .736 projectile (or larger) in a B&S. If anyone should experience a chambering issue, it is time to back up and figure out what is different before proceeding (ie. before pulling the trigger).

I personally use the Cheddite and Fiocchi plastic case (UEE) because that is what worked in my Evans. I did not spend much time with the Federal paper, but will revisit it when I continue working up new loads.

The question, as I believe you are bringing up, is - Does RM have a oval bore "bore rifle" or an oval bore "Ball & Shot gun". RM indicated a weight of 8.5 lbs, too heavy for a normal Paradox type and maybe a little light for a bore rifle. I am interested in the maker and date of completion. This may shed more light on how to approach the loading process.