The gun is based on a Confederate pistol although the caliber is not typical of the Confederate pistols of this size.
The Confederates specified that the gun companies that wished to make Cap & Ball revolvers for them should use the .36 caliber Colt "1851 Navy" pistol as the model to copy.
To simplify production, the Colts octagon barrel was often (but not always) made round by the Confederate companies.
Also, due to the need for iron and steel in the South for other tools of war, brass was often substituted for the Colts iron frame.
The caliber of the pistol in the photos is the creation of the Italian companies who felt that a .44 caliber gun would be more attractive to buyers in the US so they cut the clearance for the larger area of the cylinder (the rebated or stepped area) in the frame and installed what basically is a cylinder for the Colt 1860 Army .44 caliber pistol.
These brass framed guns are safe to shoot but it is advisable to use fairly light powder loads.
A load of 18-23 grains of 2Fg, 3Fg black powder or Pyrodex RS or P or some triple 7 powder will work well.