I think the biggest factory O/U double rifle I've seen was a 470NE as well. However, I have two rifled barrel blanks on order for 12 bore. I have an old Valmet Lion that I'm going to convert to a 20" 12 bore rifle, with quarter rib, and front "MOON" sight. This for going into the weeds with wounded Leopard, and lion. Solid Hardened lead bullets crimped into all brass cases, should do the trick, and make a legal rifle for use in "Shotgun slug only" areas for deer, and moose. It has a single selective trigger, that in 30 years has never failed to work like a two shot simiautomatic! These rifled barrels will replace the smooth bore ones that are already set up with the sights.