Some of the guys on the AR forum have shot the new .450-400, and say that as the weight is closer to the 9.3X74 No. 1, the recoil is brisk. A couple of years back, some of us tried to rattle Ruger's cage about the .470. I sent a letter, and got a reply from Ruger saying they track written requests and go over the interest level at periodic product meetings to see if a particular chambering merits the costs of going into production.