Caliber is the number of bore diameters in the length of the barrel. The 16" guns on the Iowa class battleships were 50 caliber. The 16" guns on the South Dakota class were 45 caliber. The 105 mm M68 gun on the M60 and early M1 tanks was 50 caliber. A .308 dia bore in a 24 inch barrel would be right near 78 caliber. Lately many confuse bore dia with caliber. It's become so common that now it is the accepted practice. Kinda like calling a magazine a clip.
Go tell the Spartans,Travelers passing by,That here,Obedient to their laws we lie.
I'm older now but I'm still runnin' against the wind
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