Okay, Ron brought up a point that his state required the use of a bullet larger than .40 caliber in it's muzzleloading whitetail regs. Illinois isn't the same. This got me curious as to actually how many states have this requirement. And since I am primarily on my rear end till the Doc's actually see fit to get off of theirs and fix me dang knee I have some time on my hands. Here are all the states with this requirement.

Colorado (Elk and Moose)
Iowa
Kentucky (Elk)
Montana

There were a few more that had this requirement for ML pistols but allowed .40 for rifle. I also noted a couple that allow for Lead or Jacketed bullets but no copper solids! That one was interesting.