Need to realize the restrictions in Colorado on elk hunting for your recommendations. .50 cal minimum, conicals can be no more than 2X caliber in length, NO SABOTS allowed, NO Pellets allowed, no scopes ....well, here:

a. In-line muzzleloaders are legal.
b. Must be single-barrel and fired from the shoulder.
c. Must fire a single round-ball or conical projectile the length of which does not exceed twice the diameter.
d. To hunt deer, pronghorn antelope or bear, they must be .40 caliber or larger.
e. To hunt elk or moose, they must be .50 caliber or larger.
f. From .40 caliber to .50 caliber, bullets must weigh at least 170 grains.
g. If greater than .50 caliber, bullets must weigh at least 210 grains.
h. Shotshell primers are legal.
i. Pelletized powder systems prohibited in muzzleloading seasons.
j. Cannot be loaded from the breech in muzzleloading seasons.
k. Only open or iron sights allowed in muzzleloading seasons. Scopes prohibited. Fiber optic sight paints are legal. Artificial light, batteries and electronic gear are illegal.
l. Sabots are prohibited in muzzleloading seasons. Cloth patches are not sabots.
m. Smokeless powder prohibited in muzzleloading seasons. Black powder, Pyrodex (granulated, not pellets), Clear Shot, Clean Shot and Triple 7 are legal.