I'm surprised it doesnt say the projectile size instead of muzzleloader size. Kind of ambiguous.
How it is ambiguous? The side of the barrel will show the bore size. If it is .45 or larger it is legal for elk.
I think he's talking about the case of using sabots. My muzzy is .50 cal, but the bullets are .458 cal. There were sabots for .452 cal, and I'd imagine you could probably find some to run even small diameter bullets.
I understand that but don't find the language ambiguous. It refers to the rifle, not what is shot from it.
Rereading it, you are right. I was thinking of projectile size and sabots.