I would suggest going to U tube and looking at all the different types 1st.
Some have a Wedge holding the front of the pistol on.
some cannot use Conical led bullets only ball lead.
Some have very short barrels and others have very long barrels./
some are Brass framed, and will stretch over time if your loading Hot.
some have very nice Target sights and others have a V notch & a tiny front sight.
they come in 36cal and 44 cal. The 36 is very pleasant to shoot.
There is alot more,..so take a look at what style you would like,..and go from there.
Do not buy a Neglected pistol that hasnt been cleaned regularly,...it will have a lot of corrosion.
OH, and make sure you watch "how to load" video's , or you will have a hand grenade due to a chain fire.