I don't know what DART is but replica cap and ball pistols are made with Brass frames and steel frames.
The original Union pistols (Civil War) were steel framed guns.
The Confederates made copies of the Colt (open top) and Whitney (closed top) pistols using brass for the frames. This was done because the South didn't have a lot of iron or steel.
To the best of my knowledge, the South never made a brass framed copy of the 1858 Remington.
Speaking of replica guns, the steel framed guns are the better choice and cost more than the brass framed guns.
This is due to the fact that the brass framed guns are weaker and the frame will stretch over time if heavy powder loads are fired in them.
I am not saying it is dangerous to fire one of the brass framed guns, just that they wear out faster than a steel framed replica.
If your not interested in shooting the gun, and your not the type to insist on historically correct pistols, the brass framed gun still has the feel of an original and can be a nice touch with the past just hanging on a wall.
As your gun was made in Italy, you can determine the year it was made by looking for the little square box adjacent to the proof marks. It will have letters or roman numberals in it.
Follow this link to a site which will tell you the year of production these letters/numberals represent.
PROOF MARK YEARS