For artillery it's the length of the barrel as a ratio of the diameter of the bore. Thus a 12" cannon is considered 50 caliber if the barrel is 50 feet long.
But just to confuse and frustrate outsiders, rifle and pistol calibers are a mess, and cartridge naming conventions are even worse. "22 caliber" is anywhere from .217 to .229 and includes 5.5mm, 5.56mm. "38 caliber" pistols are actually 35 caliber, which is actually 9mm, although a 9mm pistol has a different bore diameter in Russia than in the rest of the world, and a .35 caliber rifle uses a bullet .002" or .003" larger than the typical .357" bullet a .38 caliber pistol takes, which is .002" larger than the standard .355" that is a 9mm pistol. And if it's a black powder firearm or using pure lead bullets, expect those to be a bit fatter regardless of what caliber they're called. 9mm rifles, which are pretty rare, use the same .355" bullet diameter as the pistols. And it goes on and on. A .44 Magnum is actually a 42.9 Magnum, using a .429" bullet, whereas a .43 Spanish rifle used a .430" bullet. And then there is anything designed in England, which will be a few thousandths off standard just because of bloodyminded Englishness.
All of these oddly categorized bullet diameters pale beside cartridge naming conventions. That same .43 Spanish was also known as the 11mm Spanish, the 11.15x58R, and the 43-77 if the cartridges were made by Remington, which is the same company as Union Metallic Cartridge, also know as UMC.
Gun people just can't get anything squared away. Even the "science" they use to see how aerodynamic bullets are, what they call the BC or Ballistic Coefficient, is a noodle headed scheme that breaks down into half a dozen or more sub formulas and changes with velocity. Actual science uses Drag Coefficient, which is applied to everything else on earth that moves, of any size, at any speed.
Size of the hole.
ReplyDeleteSo, um, you're saying politicians are over bored and under stroked with lead in the head. All righty then. "The size of the hole DOES matter."
DeleteFor artillery it's the length of the barrel as a ratio of the diameter of the bore. Thus a 12" cannon is considered 50 caliber if the barrel is 50 feet long.
ReplyDeleteBut just to confuse and frustrate outsiders, rifle and pistol calibers are a mess, and cartridge naming conventions are even worse. "22 caliber" is anywhere from .217 to .229 and includes 5.5mm, 5.56mm. "38 caliber" pistols are actually 35 caliber, which is actually 9mm, although a 9mm pistol has a different bore diameter in Russia than in the rest of the world, and a .35 caliber rifle uses a bullet .002" or .003" larger than the typical .357" bullet a .38 caliber pistol takes, which is .002" larger than the standard .355" that is a 9mm pistol. And if it's a black powder firearm or using pure lead bullets, expect those to be a bit fatter regardless of what caliber they're called. 9mm rifles, which are pretty rare, use the same .355" bullet diameter as the pistols. And it goes on and on. A .44 Magnum is actually a 42.9 Magnum, using a .429" bullet, whereas a .43 Spanish rifle used a .430" bullet. And then there is anything designed in England, which will be a few thousandths off standard just because of bloodyminded Englishness.
All of these oddly categorized bullet diameters pale beside cartridge naming conventions. That same .43 Spanish was also known as the 11mm Spanish, the 11.15x58R, and the 43-77 if the cartridges were made by Remington, which is the same company as Union Metallic Cartridge, also know as UMC.
Gun people just can't get anything squared away. Even the "science" they use to see how aerodynamic bullets are, what they call the BC or Ballistic Coefficient, is a noodle headed scheme that breaks down into half a dozen or more sub formulas and changes with velocity. Actual science uses Drag Coefficient, which is applied to everything else on earth that moves, of any size, at any speed.
"Another fine mess you gun makers have got us into" O Hardy. Thanks Drew for the info.
Delete