Schmit-
I don't think the 45-70 would fit for Urban Rifle, for the very reasons Pat states...overpenetration.
http://thefiringline.com/Misc/tanzan...-Buf_Bore1.jpg
I wonder if the 30-30 might not be suitable in the right hands?
As for the Co-Pilot....great gun. I prefer the variant made by DRC Custom (David Clay) myself. Higher cool factor; higher bomb proof factor.
Rich