Mark,
I have no hard evidence, so if I am off base here, I am open to correction.
My dad owned a 264 Win Mag and was his favorite hunting gun, but one year he put in for a draw in the Mountain West for Elk (back in the early 1970's). To prepare for the hunt, dad purchased a 7mm Mag, because.....as the story goes....the state where he applied required at least a .27 caliber, for which his 264 would not fit the bill.
Maybe this was a great story for Mom, allowing dad to purchase, yet another gun.....hahahahaha
I do not remember which state.
I think Colorado requires at least a .24 caliber with at least 1,000 pounds of energy at 100 or 200 yards.
Oregon requires .24 caliber.
