The following sites sell 38 S&W (not the special) ammo.
https://www.buffalobore.com/ They sell one cartridge at this site.
38 S&W (38 COLT NEW POLICE) - 125 gr. Hard Cast FN 1,000 fps
That rating is for a 4 inch barrel, if you use a 2 inch it's rated about
900 fps. Not the most powerful thing out there but acceptable.
There are some old time top open revolvers to weak to shoot this
crtg. The info about that is on their site. Last time I checked it was
in stock and available.
The Old Western Scrounger LLC. They sell two or three crtgs. for the 38S&W
The one I bought is the 38/200. A large grain but slow crtg. I believe
it's rated something like in the 500 fps to 650 range. So you can
shoot it in most any 38 S&W. You may have to order and be on a
waiting list for it to be shipped. They told me it would be several
weeks before I received mine but to my surprize it arrived about ten
days later.
I have bought from both places and had no trouble with the order.
I use my J frame 38 S&W for protection. I alternate those two crtgs
in the cylindar so I would be using both if I ever have to shoot for
real. Both these places charge way more than they should but when
your the only game around you get to set the rules.
Hope this helps. Goose