Gator:
First, welcome to the Forum.
Yes, I think I can help you with the marking interpretation. This information comes from the Victory Model Database, which my pal LWCmdr45 and I administer for the benefit of collectors. We are always looking for new information for the Database. Accordingly, would you please post here or PM me with the complete serial number, barrel length, left top strap markings, any butt markings, caliber, and any post-factory modifications or markings? That info will be incorporated in the Database on a confidential basis. That information helps us to continually improve and refine the Database to help guys just like you.
Now, turning to your revolver, I suspect that there is more to the marking than just S-Kar 305. As these markings were hand-stamped the markings can sometimes be indistinct or worn over the years. I suspect that the complete marking is/was more likely "WB-S-Kar 305". That would translate to Würtemberg-Baden - Stadtkreis - Karlsruhe -305.
The meaning of that marking is this. Your revolver was one of those provided post-war to the West German government to arm law enforcement agencies. In this case it was the police in Karlsruhe and the revolver got the rack number of 305. These guns were used from the late 1940s up until the mid-50s or so, and were then surplused and sold on the civilian market. Many returned to the USA.
Based on the similar examples found in the Database I am going to guess that your revolver is a 4 inch barreled .38 Special. How did I do on my guess?
I hope this information is helpful to you and I hope further that you will provide us with the data on your gun for the Database.