Mark7/50 caliber
Mark 7 16-inch/50-caliber gun
BB64 is the Wisconsin
You may ask why is it a 50 caliber?
length of barrel in inches divided by diameter of the shell.
There is a shooting range in Arnold Missouri that has 2 of the 16 inch practice rounds (blue with no explosives or fuse) flanking the entrance to the club house.
I wonder how many of these guys were wearing hearing protection.
