Welcome to the forum.
the XX9 indicates it was proof tested in 1973.
The other two marks are the Italian proof stamps.
24477 is the serial number and the fact that the number 477 is on the barrel indicates this is the original barrel.
I can't say who made your pistol because all of the Italian companies must have their guns proof tested.
There are sometimes other markings on Italian reproduction pistols that indicate the makers company.
One that looks like a rifled barrel with a capital U in the center is Uberti.
A palm tree in a circle indicates Palmetto.
FAP indicates the gun was made by F.LLI Pietta.
You didn't indicate whether your gun has a brass or a steel frame. Almost all have brass trigger guards and grip backstraps but I am speaking of the frame or receiver of the gun.
My reason for asking is that generally speaking the brass framed guns are not as strong and most people recommend using somewhat smaller powder charges in them.
I suppose I also should point out that the original Colt 1851 was a .36 caliber gun.
That's not bad mouthing your gun as the .44 caliber guns are, in my opinion, more fun to shoot.
If you do shoot it, don't be surprised if it shoots high. Most of the Cap & Ball pistols do.
I hope this helps answer your question.