What I am about to say is from my poor memory quoting an old published railroad story that may not have been factual:
the railroads leaving El Paso, TX westward allowed the train service crews to carry guns for protection. The railroad would not provide guns, but would buy or reimburse for the ammunition.
I also cannot provide a time frame for this statement, but common knowledge of the area would say that guns would be a necessity for protection since the first track was laid until present date.