New Federal v old FC?
Isn't it the other way 'round?
I have a bunch of new production Federal 9mm ammo (American Eagle and HST) and it's marked FC, not Federal.
I know there was some problems w Federal 40 S&W ammo a few yrs ago, and the 40 cases were tweaked... 155 HS and 180 FMJ to be specific. Blew cases in guns other than Glocks too BTW.
The new HST ammo I have was made long after those problems were discoverd and fixed, and they are marked FC. ;b