For comparison, here are the throat measurements other S&W .45 ACP revolvers in my collection:

Model 1917 from October 1918: .453"
Model 1950 Army Pre-Model 22 from June 1952: .455"
.45 Cal. Model 1950 Pre-Model 26 from April 1956 : .455"

Considering that the Model 1917 was expected to be used in trench warfare conditions, you would think that one has the most generous chambers. It does have a 0.010" barrel cylinder gap which seems logical.