Last I saw on this was they were going to allow rifles that shoot pistol cartridges (straight-walled cartridge)must be 1 1/16th in min and a maximum of 1 3/4 in. They did the maximum I'm assuming because you can get into some serious powered rifle up above that range. You figure you can hand load 45-70 to reach out to 400 yards with out trying too hard. But I don't know if this law has gone into affect or not.