Just so you know, the headstamp, or markings on the head of the brass HAS NOTHING to do with the caliber of the ammunition in this case. That is a military headstamp with the FNM indicating the manfacturer, the 81-19 indicates a year and manfacturing code.
Military ammunition headstamps are all codes. Civilian headstampe USUALLY indicate the caliber.
The second admendment GUARANTEES the other nine and the Constitution!