I just got bacl from the SCI Convention. At the show got a double rifle in 17 bore made by;
William Lee
28 Lancaster St.
Birmingham
It has about 1 in 60 inch twist and is chambered for the 20 gauge brass case loaded with a 17 bore projectile. It came cased with a late round ball mold but the greenhill formula figures that it will take a bullet up to 1.05 inches long.
Any information on loading or this maker would be of a great help.

do you have buy the gun, how much was it. I would say its a very old one, made for 1880. rifled bore gun in old times where made for "thick" paper cases. if you measure an 20bore paper case believe you will find that your roundball wiil fit it. you have get 20 bore Magtech brass, 2,5" long, with the gun?
I recommend the RCBS shotshell die set 20 bore. you have all you need: case holder, resizing die and crimp die. aneal the brass case every time.I load in my 20 bore cape gun(steel barrels) over hundred grain ffg under a 420grain brennecke slug. cicle fly wads have good wads, load it under the roundball and crimp the case.

Do not short the round ball as a projectile. In many ways it's a better hunting load than the conical. The conical had an advantage in a military context where it carried better at long range, but the increased initial velocity of the ball makes better sense at sporting ranges, say <200yd.

The rifle is chambered for brass case with lead bullet.
Yakama

Do you have any information about it's regulation load?

There are lots of places to get molds made. That will not be a problem. If the gun will regulate with a bullet, then you are in business.

Brent

The rifle has no information on it and nothing in the case. It had a dixie gun works round ball mold and some berdam primed brass cases with it. The twist of 1 in 60 leaves me thinking that it my not uncross the bullets with a round ball at any load level that would be safe.
I will be working with this mold and black powder over the next couple of weeks and will post my findings.
Yakama