Thats a standard new service or model 1917 Army that has been customized. U.S. Property stamp on the barrel is from a 1917 Army. New Service pistols had the caliber marking just like what is shown as well, except they had
New Service before the caliber.
Can see it but not read it on this 1920's 38 WCF New service of mine.
Here is the U.S. Property stamp on my 1917 Army, made in 1918.
The rear sight is also wrong for a shooting master, but that may be part of the King's rib. The shooting master also has shooting master stamped in the barrel, to the left of the caliber marking.
My Shooting Master does not have that screw above the cylinder latch either. Mine looks like it was shot with magnum loads, a lot. Its plain worn out.