My father had the contract with the Post Office Department to meet all of the trains that came into Amarillo and transfer the mail to the P.O. and between railroads (three). I used to work for him part time and have gotten the mail off of hundreds of R.P.O. cars (not to mention bumping my head on that damned hook that snared pouches while the train was moving). The clerks did indeed carry pistols and I'm thinking Colt Detective Specials. They would ride with me in the truck to the Post Office and then go to their hotel. Occasionally we would carry the payroll for Amarillo Air Force Base in cash. One clerk with one pistol would accompany me to the Post Office with that cash. When the Air Force came to pick it up, they would send four people... two to handle the pouches and two who were armed with Thompson submachine guns to guard it. We also carried cash for the banks. I'm sure this sort of thing went on all over the country. I never heard of a robbery, but it would have been very easy in the scheme of things.