Granted, this is a hypothetical, but my daily carry piece is either a .38 special or a .380 ACP. Neither of those, as far as I know, was ever considered a government cartridge, although the .38 Special does have a long history with the military.
However, arguments can be made that the .45 ACP was neither designed nor marketed by the government, but was designed by John M. Browning for Colt. The military adopted the cartridge, just as it adopted other cartridges, both before and after. The .30 Govt 06 is one cartridge that might be considered a government cartridge,as it the .45-70 Govt, although we might make the argument that the .45-70 was simply a government adoption of a civilian designed cartridge.