First, it isn't a muzzle loader. It does NOT load from the muzzle. There have been two manufacturers of the brass framed long barreled Remington style frame cap and ball revolvers. Pietta, makes them for Cabelas and Palmetto, which unfortunately went out of business about 16 months ago. Both are/were Italian. Some where on your gun you should find a stamp ing of letters such as AB or AH. You will also find a proof mark. Italian law requires all guns be proofed and marked with the year of manufacturre. The letter code starts around 1951 with A and goes forward. The table of dates is available on sites dealing with cap and ball revolvers.
While the brass frame guns appear strong, the brass actually can stretch after multiple repeated heavy charges. Kind of like hitting a piece of brass 100 times with a tack hammer. The brass will start to deform.
Keep the powder charges low, but you want enough powder and or filler that there is no space under the balls when seated. The max charge for your 44 chambers is probably around 30 to 35 grains. The rammer will only seat the ball so far down the chamber so, if you must, use around 20 grains of 2fg and another 10 grain volumn equivalent of filler, like cream of wheat commonly referred to as COW in several web sites. COW compresses rather uniformly and has worked for 50 years for shooters. It is cheap. Some things do not compress uniformly and you want each chamber loaded as uniformly as possible.
Some shooters use wonder wads on top the powder and under the ball. Other shooters put the ball right down on the powder and use a grease lube on top to seal the chambers.
Mt thoughts are that, especially with that long barrel, you want to havee some lube coat the bore as the ball is pushed down through to the muzzle. That will cut down on leading the bore, and will also leave a slightly greasey coating on the bore before the powder fouling has a chance to hit the bore.
The purpose of sealing the chambers is to prevent chain fires, ie more than one chamber firing at a time. Most folks can go through life firing tens of thousandes of revolver rounds without a chain fire. All it takes is once to scare the, well cause a need for laundereed shorts. It can also be very dangerous. I have seen a cap and ball revolver with the side of the cylinder blown off.
To prevent chain firing, you need to load balls that are just over chamber size to the point that a thin ring of lead is shaved off the ball as it is rammed into the mouth of the chamber. A chamber diameter fibre wad between the powder and the ball can work. smearing lube on top the ball to seal the chamber is messy, but lubes the bore and keeps fouling somewhat softer as well. Some folks use shortening. When the gun gets hot, or on a hot summer day, shortening can really make a drippy greasy mess.
Also, always keep all loaded chambers capped when shooting. Fire has been known/theoretically to spit out through the nipple and reach into an uncapped nipple.
And lastly the old story of load five and let the hammer rest on the empty, for safety, although most modern made repros have cylinder notches in between the nipples for the hammer to rest.
98% of such guns are indeed 44 caliber and require a 451 or 454 ball. the 457 used by the Ruger Old Army is too big for your gun. A very few were made in 36 cal., I am assuming that yours is the 44 caliber.
They are a great deal of fun to shoot. Most of the Italian long barrel guns are not that accurate. Perhaps a pie plate at 25 yds. Although a few are capable of much better accuracy.
Because it is not a muzzle loader, it is not legal for most hunting in PA. The exceptions are ground hogs and coyotes.
There are some cylinders available to convert the cap and ball revolvers to 45 colt. BUT NOT IN A BRASS FRAME GUN.