Some of you might be confusing the OP on his elk hunt here in Colorado.
Here are the regulations as far as a muzzle loader here:
2. MUZZLELOADING RIFLES & SMOOTHBORE MUSKETS
a. Only legal muzzleloaders allowed in muzzleloading seasons.
b. In-line muzzleloaders are legal.
c. Must be a single barrel that fires a single round ball or conical projectile.
d. To hunt deer, pronghorn or bear, conical bullets must be a minimum of .40
caliber, and round-ball bullets must be a minimum of .50 caliber.
e. To hunt elk or moose, conical bullets must be a minimum of .50 caliber, and
round-ball bullets must be a minimum of .54 caliber.
f. From .40 caliber to .50 caliber, bullets must weigh a minimum of 170 grains.
g. If greater than .50 caliber, bullets must weigh a minimum of 210 grains.
h. Shotshell primers and B.O.R. Lock MZ System bullets are legal.
i. Pelletized powder systems are prohibited during muzzleloading seasons.
j. Cannot be loaded from the breech during muzzleloading seasons.
k. Only open or iron sights allowed in muzzleloading seasons. Fiber optics
and fluorescent paint incorporated into or on open or iron sights are legal.
Scopes or any sighting device using artificial light, batteries and electronic
gear are prohibited during muzzleloading seasons.
l. Sabots are prohibited during muzzleloading seasons. Cloth patches are not sabots.
m. Smokeless powder is prohibited in muzzleloading seasons. Black powder
and black-powder substitutes are legal.
n. Electronic or battery-powered devices cannot be incorporated into or attached
to muzzleloader during muzzleloading seasons
As for powder, I have found Pyrodex RS just as accurate as BH 209 in both of my inlines. BH 209 is cleaner but not by much.
Purchasing a Remington Ultra ML is really not in play unless the OP wants to shoot 600+ yards. I know a hunter who had a tag in Utah for the Monroe unit and missed a great bull because he figured that he could drop it at 675 yard with his Remington, it didn't happen. He could of gotten much closer but figured that his rifle would do the job with a scope on it and the range dialed in.
In Colorado you can not use a scope or 45 caliber bullets for elk. Open sights and a minimum of 50 caliber. A muzzle loader hunter also is required to wear
at least 500 square inches of solid daylight
fluorescent orange or fluorescent pink material on an outer garment above
the waist while hunting deer, elk, pronghorn, moose or bear with any firearm
license. A fluorescent orange or pink hat or head covering, visible from all
directions, is also required.
I think that we need to keep or conversation to the laws that are in effect here in Colorado to avoid causing confusion.