Last August, we got 7 rounds into about 8" using a 1.5" smoothbore cannon, shooting 1.4" balls cast of WW. That group looked absolutely devistatingly awesome - well, yiou get the drift! I can hardly wait to see the results of this 'rifle'!!!
Now BigDog, is the bore diameter about 1.35" or is the groove diameter 1.35"? If the latter, that would make the bore diameter around 1.3" with 020" deep rifling, which it appeared in one of the first pictures. I'd be using a ball around 1.28" ball and about .030" denim for the patch" in a 1.3" bore with pure lead balls and perhaps .020" for WW balls. I've never dealt with numbers this big before, that weren't mounted on wheels.