[Darth Kur]

My friend recently acquired a rather vintage S&W revolver in the 38 Special caliber. At least that round fits securely in the cylinder so I am assuming that is indeed what it takes. What I am wondering is that if it is a very early example of this round might it not require black powder cartridges rather than smokeless? There are no indications of a model number present nor caliber upon the gun itself. The only writing, other than the large S&W insignia on either side of the frame, is a small grouping of patent dates on the top of the short barrel and a four digit serial number in three separate locations. It has a 6 shot swing-out cylinder and intricately detailed black hardened rubber grips. The serial number is 3954. The writing on the barrel is as follows: S.A. Pat Jul 1 84, Dec 2 96, Oct 4 98. See attached pictures below for further details.
Could someone please indicate what year this might have been made, what model it might be and what particular rounds it will require? It would be much appreciated.
Thank you.