Convert from football field [U.S., complete] to caliber

Unit Definition (football field [U.S., complete])
The football field is a common informal unit of distance in the United States and Canada. Americans aren't quite agreed as to whether the unit is exactly 100 yards (91.44 meters), the distance between the goal lines on an American football field, or 120 yards (109.728 meters), the 'complete' distance including the two end zones. Canadian football fields are 110 yards (100.58 meters) long between the goal lines and 150 yards (137.16 meters) including the end zones. The football field is also used sometimes as an informal unit of area: including the end zones, an American football field represents an area of 1.3223 acre or about 0.535 hectare while the Canadian football field has an area of 2.0145 acre or 0.815 hectare.

Unit Definition (caliber)
The caliber is a unit used to express the bore diameter of a gun. Traditionally, the diameter is stated in inches, so that ".22 caliber" refers to a pistol having a bore of 0.22 inches (5.588 mm). So the caliber is actually equivalent to the inch. The usage of the term "caliber" is actually now in decline, because bore diameters of many guns are now stated in millimeters. "Caliber" is the American spelling; elsewhere the unit is often spelled "calibre."