How long is 40 calibers?

Answer 1

For every weapon except large naval guns mounted on ships, caliber mean the diameter of the bore. Thus caliber almost always means thickness, instead of length. "40 caliber" thus usually mean .40 of an inch. So modern handguns of .40 caliber fire bullets 40/100ths of an inch in diameter. Depending on the weapon in question, the length of the cartridge (which is the bullet plus a brass shell case holding the propellant) which fits the weapon might vary. Even if the caliber is the same, the cartridge must fit into the weapon's chamber to fire safely, or at all. The length of the barrel could be anything the manufacturer desires, but, the longer the barrel the better the accuracy possible; however, a longer barrel makes the weapon heavy and hard to hold steady on target for many shooters.

Caliber in reference to naval guns gives the length of the barrel. In naval terms this is figured by dividing the bore diameter into the length of the barrel. Thus, US battleships in WWII mounted a main battery of 16-inch, 45 or 50 caliber guns. A 16 inch/45 had a barrel 45 times 16, or 720 inches long, or 60 feet. The last four had 16/50s, which were 800 inches long, or 66 2/3 feet. All had a secondary battery of five inch (bore diameter) 38 caliber guns, so their barrels were (5 X 38) 190 inches, or 15 feet, ten inches. The largest gun placed on modern US ships is an autoloading 5 inch/54 caliber, so its barrel is (5 X 54) 270 inches long, or 22 1/2 feet. But, again, caliber as a function of barrel length applies only to naval guns.