In 2010, there was a news about the British sniper, which said that this sniper broke the ultra-long-range sniper killing record with an 8.59mm caliber sniper rifle in Afghanistan. At that time, someone asked: "What is that 8.59mm sniper bomb?" When I arrived, I realized that the 9.59 sniper bomb was the .338 Lapua Magnum bomb.
In fact, in many cases, the name of the caliber is also meaningful and does not represent the actual diameter of the warhead.
For example, the .357 Magnum bomb (.357 MANGUM) and the .38 special bomb (.38 SPECIAL) have the same diameter of 9.1mm.
The diameter of the .38 super bomb is actually 9.02mm, but the diameter of its shell is the same as that of the .38 special bomb, which is 0.38 inches. Now you should understand how the .38 bomb comes from. Right? It does not refer to the diameter of the bullet or the diameter of the mouth of the shell.
As another example, the civilian name of the 7.62x51mm NATO bomb is .308 Winchester (.308 WIN), and the .300 Winchester-Magnum bomb (.300 WIN MAG) is also called 7.62x67mm, although one It's called .308, and one is called .300. It seems that the diameter of the latter is smaller than the diameter of the former, but in fact both have a diameter of 7.8mm. The 7.62 is actually the diameter of the male line of the gun barrel, because the caliber name of some bullets is named after the diameter of the male line, while the caliber name of others is named after the diameter of the female line.
This is not only true for English names, even for metric names. For example, the diameter of the 5.56 NATO projectile is 5.7mm (0.224 inches), and the projectile diameter of the FN 5.7x28mm is also 5.7mm. The two projectiles have the same diameter, but they are called differently in the name. So how did the 5.56 NATO bomb come from? Looking at the following picture, regardless of the military-standard 5.56mm NATO or the civilian version of the .223 Rem, the inner diameter of the other bombs is 0.219 inches, which is equivalent to 5.56mm.
It is also common to have two or three names for the same caliber. For example, the German 7.92x57mm rifle ammunition, also called 8x57mm or 8mm Mauser ammunition, was also called the "seven nine" ammunition in the old society. In fact, the projectile's projectile diameter is 8.1mm, and 7.92 or 7.9 are male diameter.
There are also some different calibers, but the same or similar bullet diameters result in the same number in the name, so you need to add a suffix to the complete name to show the difference. For example, .357 Magnum and .357 SIG, Magnum and SIG at the back indicate that these two .357 are actually different calibers. Just like the metric names 7.62x39 and 7.62x54 R, the number after the multiplier sign indicates that the two 7.62 are two calibers, and 7.62x54 R is followed by an R to indicate the bottom edge of the shell It is prominent, if one day you invented 7.62x54 without flanges, do not add R, because the bottom edge is different, the gun machine is so difficult to use.
There are many examples that I will not list one by one. In short, the actual bullet diameter may have been calculated, tested, improved or patted on the head, but what is the name of this caliber? It may be called according to the actual size, but it may also be conceived by patting the head.