On the Detroit PD, most cops who were at all "gun guys" and even a good percentage of those who weren't, got rid of the Model 10 as soon as they were off probation. That's why so many are around in very good shape. They sat on the shelf for most of a 25-year career.

DPD policy was that after you were off probation, you could carry whatever revolver you wanted as long as it was Smith and Wesson or Colt, .38 or bigger with a 4" barrel or bigger for patrol.

Later they approved the Model 39 and 59 for carry. Later still, they approved the Model 645 for carry. After that, they went to Glocks and later to Smith semi-autos. At some point, they approved the Walther PPK in .380 for off-duty. Probably because some guy with some rank wanted to carry one.

So it would be MOST correct to see Detroit cops, in 1967, carrying a variety of handguns that fit those caveats.

As soon as I was off probation, I carried a 25-5 and later a 645.