Ok that is about how I figured it, thanks for the description. I figured either a bushing inside on the hammers or the firing pin holes or on the breech face to support the cartridge/primers and prevent too great movement during firing.

The groove diameters I measured from the chamber casts were
.362 - left
.3625 - right

I want to confirm by slugging with a lead ball or cerrosafe further down the barrel.

I am also still working on getting some S&B ammo.

Last edited by L3n4rd; 08/12/15 08:59 AM.