I'd say the chances of it being a Military and Police are EXCELLENT, given that there were millions of these made and they were available after the war very inexpensively.
When you take the pictures, lay a ruler along side the gun, along the top of the barrel.
This will give a definite size reference. S&W's revolvers are SO similar looking that without a size reference it can often be very difficult to tell the frame size.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.