Finally some time with Buffalo Classic; Slugging the barrel and especially the throat which appeared to be very non-existent when looked through the chamber with flash light. That was pretty much right, not too much throat in this rifle. Groove dia is .4555" and bore .4515"; almost can't believe that groove diameter. "Throat" style you'll see from the pic:
My .459" Marlin boolits with tapered front band were literally engraving, lands were cutting chips when forced in to the rifling... Some work ahead I guess.