I was going to bet on the wrong horse in this one......
from THE AMERICAN HERITAGE DICTIONARY:
"b. The diameter of the bore of a firearm, usually shown in hundredths or thousandths of an inch and expressed in writing or print in terms of a decimal fraction: .45 caliber. "
From MERRIAM-WEBSTER:
"b : the diameter of a bore of a gun usually expressed in hundredths or thousandths of an inch and typically written as a decimal fraction <.32 caliber>"
Anyone else get the idea these dictionary guys read each other's books pretty closely?
Incidentally, using caliber to refer to barrel length is a rare use of "caliber". I referenced 10 dictionaries, and only one included a definition of caliber as a barrel length measure.
Secondly, as an aside, there is no reason why a proper noun should not include a ".". A name is a choice not governed by the spelling police, as any teacher is sure to be reminded of the first schoolday of every year.... Dutch.
