It is, as you think, a Smith & Wesson Military and Police Model, square butt model.
The serial number puts its date of manufacture at sometime near the end of 1953, one of the last years that they used the half-moon front sight.
Supica and Nahaus' book The Standard Catalog of Smith & Wesson says that the change from the round front sight to the ramp front sight came in 1952, but that was done over time as previously manufactured parts were used up. In other words, your barrel was manufactured sometime before the change took place, placed in ready reserve storage, and as orders came in for the 2" models, was assembled onto the gun and the unit serial numbered.
So, given its manufacture date, it would appear that he got it after he ended his service as sheriff.
"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.