Colorado is slowly catching up with the other states. To think it was only a few years ago when inline blackpowder rifles were not legal.
3. MUZZLELOADING RIFLES & SMOOTHBORE MUSKETS
a. In-line muzzleloaders are legal.
b. Must be single-barrel that fires a single round-ball or conical projectile
the length of which does not exceed twice the diameter.
c. To hunt deer, pronghorn or bear, they must be .40 caliber or larger.
d. To hunt elk or moose, they must be .50 caliber or larger.
e. From .40 caliber to .50 caliber, bullets must weigh at least 170 grains.
f. If greater than .50 caliber, bullets must weigh at least 210 grains.
g. Shotshell primers are legal.
h. Pelletized powder systems prohibited in muzzleloading seasons.
i. Cannot be loaded from the breech in muzzleloading seasons.
j. Only open or iron sights allowed in muzzleloading seasons. Scopes prohibited.
Fiber optic sights and fluorescent paints are legal. Artificial light,
batteries and electronic gear are illegal.
k. Sabots are prohibited in muzzleloading seasons. Cloth patches are
not sabots.
l. Smokeless powder prohibited in muzzleloading seasons. Black
powder, Pyrodex (granulated, not pellets), Clear Shot, Clean Shot
and Triple 7 are legal.
... and this kicker ...
m. Only legal muzzleloaders allowed in muzzleloading seasons.