CF, That is interesting. I wonder if it is possible these were not the handguns they used as their duty weapon but rather new handguns presented as a retirement gift. Meaning they were purchased with nominal donations by fellow officers combined together for a farewell retirement luncheon gift. At least the fact they were specially engraved leads one to thing this.
The above is just a guess on my part since I do not know. I know things change over time, but I am not aware of Federal Government Property ever being gifted to a retiring employee. Even U.S. Flags flown over the Capitol are paid for out of private funds when gifted.