Appears you have a S&W Victory model, mid-WWII. If it is stamped .38 S&W, then it is not to be used with the .38 S&W Special cartridge. In that caliber, it was almost certainly intended for use by UK forces. Front sight does not appear original. This gun is more or less the same as the S&W Model 10 M&P.

.38 S&W ammo is a little hard to find, but it is still loaded. A local dealer can probably order it for you if he does not stock it.

You can Google on S&W Victory Model to find out more about it. These are fairly common, and in original condition can bring a good price. Unfortunately, yours has been modified and would not be worth as much as one with the factory front sight and grips.