Welcome to the forum.
I'm not sure how much experaince you have with muzzleloaders so I'll assume your kind of a newbie and you want to shoot it.
The pictures I saw on the google link show the rifle to be a nice gun.
It's 1 in 20 rate of twist is made to shoot long bullets and usually, the rifling in these barrels is rather shallow. That makes shooting a patched roundball not a very good option.
That leaves bullets as the best choice.
Track of the Wolf, a very reputable company, has bullets they say is for a .451 caliber barrel.
They are shown on the page in the following link.
https://www.trackofthewolf.com/List/Item.aspx/129/1
These bullets might work as received or they might need resizing to fit into the barrel.
They should be about .001 to .003 inch smaller than the bore of the barrel.
Don't be tempted to buy .45 caliber bullets made for cartridge guns. They are all oversize. .45 handgun cartridge bullets are .454" in diameter and .45 rifle bullets are .458".
All muzzleloaders are safe to shoot
if you use real 2Fg black powder or one of the black powder substitute powders like "Pyrodex R" or Triple Se7en powder.
Do not use 3Fg or pistol type powders like Pyrodex P.
Under NO circumstance should you try to use a modern smokeless powder of any type in your gun.
It is not made to take the pressures modern smokeless powders will make.
You will need percussion caps to detonate the powder. Look for #11 size caps.
You should start with a powder load that is about 50 grains of 2Fg black (34 grains actual weight if you are using one of the synthetic powders).
I don't think it's wise to go over 80 grains of real 2Fg (56 grains actual weight if you are using one of the synthetic powders).
If you are measuring the powder charge by using a volume type measure like most of us do, the same size can be used for any of the different powder types. That is, a 50 grain by volume measure will measure out enough powder to create pressures of a 50 grain real black powder charge.
Likewise a 70 grain by volume measure will measure any of the synthetic powders needed to produce about the same pressures as the black powder.
All of these powders leave corrosive fouling after they have been fired.
That makes it absolutely necessary to clean the gun as soon as possible after your done shooting.
Plain water along with some dish washing soap works best. You do not need any of the "special" cleaning solutions for sale on the market.
As I said before, do not try to use any of the finer pistol powders like 3Fg with your bullets.
The members on the forum often substitute 3Fg powder for 2Fg powder and they get away with it because they are shooting patched roundballs.
Heavy bullets like you will be using create MUCH higher breech pressures than patched roundballs do so stick with the slower burning 2Fg type powders.
Have fun and if I didn't answer your questions please ask for more.
