Muley Hunter
Steve may have a point...
From the Colorado Big Game Regualtions:
Muzzle-loading rifles and smoothbore muskets, provided the minimum caliber shall be forty (.40) for all big game except elk and moose. The minimum caliber for elk and moose shall be fifty (.50). All muzzle-loading rifles and smoothbore muskets from forty (.40) caliber through fifty (.50) caliber must use a bullet of at least 170 grains in weight. All muzzle-loading rifles and smoothbore muskets greater than fifty (.50) caliber must use bullets of at least 210 grains in weight.
But during ML season:
During the muzzle-loading firearm seasons for deer, elk, pronghorn, bear, and moose the following additional restrictions apply:
1. Propellent/Powders: The use of pelletized powder systems and smokeless powder are prohibited.
2. Projectiles: Sabots are prohibited. For the purposes of this regulation cloth patches are not sabots.
3. Loading: Firearms must load from the muzzle. Firearms which can be loaded from the breech are prohibited.
4. Sights: Any muzzle-loading rifle or smoothbore musket with any sighting device other than open or "iron" sights is prohibited.
5. Electronic or battery-powered devices cannot be incorporated into or attached to the muzzle-loading firearm.
It looks to me like during rifle season you must use a projectile with a weight of at least 210 grains.
http://wildlife.state.co.us/SiteColl...tions/Ch02.pdf
Check page 5