Good looking gun! What calibre are Rice 12 bores?
If a true .729" to .730", you will likely need the 12 bore wads (.740") from Track.
I would use 2 3/4 drams (75gr.) 2F and 2 or 3 tin "B" wads over the powder, then 1oz to 1 1/8" shot, then a single "B" wad.
That would be my first test.
The use of thin wads beneath the shot, is to reduce the weight of the sealing wad so it does not disrupt the shot cloud at
the muzzle as heavier fiber wads tend to do. Choked bores usually do best with fiber wads & will out pattern just about ANY
cylinder choked gun without special loading. (special loading as-in shot containers)
I would increase powder charge to a maximum of 3 1/4 drams (approx.90gr.) in testing and no more than 1 1/2 oz. shot.
I would expect best shooting around 3 drams 2F (82gr.) and 1 1/8oz shot.
