I go to the Fugate Firearms site occasionally and today I saw what they are calling a "BB marked pre-70" government model. And, OK, it's got "BB" stamped below the serial number. Price is $3,100. I am only curious - now is not the right time for me to spend 3 grand on anything - does anyone know why the BB marking is important? What does it mean, and why would someone pay extra for it?