From what I have read elsewhere (keeping in mind not everything you read is true) It will be based on the .375 Ruger as the object was to get more speed than the .264 Win (assuming a 24" barrel) in a standard length action thus making for a lighter rifle. I did some poking around some load data and the 264 Win should rival it if it is a 26 inch barrel. I will have to do some testing. Maybe I'll get myself a chronograph for Christmas. Either way another 6.5 of any iteration is fine by me.