The most popular firearm calibers

The term caliber refers to the nominal diameter of a firearm's barrel or rifle in inches or millimeters. It also refers to the diameter of the bullet, and sometimes the cartridge case. Ammunition is usually named after its caliber (diameter). Caliber is measured using imperial or metric markings, depending on the place of manufacture of the cartridge. For example, Remington .223 refers to the imperial measurement of a specific cartridge with a bullet diameter of about 0.22 inches. The metric equivalent is 5.56 millimeters, and its specific cartridge is labeled as 5.56x45mm NATO (“45mm” refers to the length of the casing). Caliber markings do not always describe the size of the bullets or even exact dimensions. For example, the diameter of a Special .38 bullet is actually .357 inches, as is the Magnum .357 (.38 refers to the diameter of the casing). A 9mm bullet (0.35 inches) has the same size as the .380 ACP.

.223 Remington / 5.56 x 45mm NATO

This is a .22 caliber centerfire cartridge, originally developed in 1957 for the new lightweight battle rifle (ArmaLite AR-15). It later became the ammunition for the M16 – the standard military rifle of the U.S. Army. The .223 Remington cartridge is one of the most popular of all time and is currently used in a wide range of semi-automatic and manual rifles. This cartridge is fast, accurate, and good for beginners in rifle shooting or self-defense. It has good ballistics, low recoil, and shoots flat.

Sample Data
Bullet weight: 2.27 - 5.8 g (most commonly 3.6 g)
Muzzle velocity: 948 - 1005 m/s
Muzzle energy: 1786 J
Recoil energy: 3.2 J

.22 Long Rifle (5.6 × 15 mm R)

.22 LR is a small caliber rimfire cartridge. It is the most commonly sold ammunition in the world, used in a variety of rifles, pistols, revolvers, and submachine guns. This cartridge was introduced in 1884 and was developed after the .22 Short, the first American metallic cartridge designed for the original Smith & Wesson revolver in 1857. The .22 Long Rifle is popular among beginners and experts due to its very low recoil and relatively low noise level. It is an inexpensive cartridge found in hundreds of different firearms. It is very popular in sport shooting as well as hunting small game. It is also a great option for beginners learning how to shoot a rifle.

Sample Data
Bullet weight: 1.9 – 3.9 g
Muzzle velocity: 110 – 550 m/s
Muzzle energy: 120 - 275 J
Recoil energy: 0.2 J

.38 Special (9 x 29 mm R)

The .38 Special cartridge is one of the most popular ammunition types for revolvers but is also used in carbines and semi-automatic pistols. It is a centerfire cartridge with a rim, introduced by Smith & Wesson in 1898. It was also the standard cartridge for American police departments from the 1920s to the 1990s. It was also used in handguns by the U.S. military during World War I and II, the Vietnam War, and the Korean War. The .38 Special cartridge is also known in other parts of the world as 9.1 x 29mm R or 9 x 29.5mm R. It appeared as an improvement over the .38 Long Colt cartridge, which was too weak for the U.S. Army during the Filipino-American War, when fighting against Moro warriors.

Although the cartridge is referred to as .38, it is closer to .36, as it has a bullet diameter of 0.357 inches. The designation .38 refers to the diameter of the entire casing.

In 1934, the .357 Magnum, an improved version with a longer casing, higher pressure, and superior stopping power but greater recoil, appeared. Any .357 Magnum revolver can use .38 Special cartridges, but the reverse is not possible.
Ballistic differences between these types of ammunition are as follows:
.357 Magnum:
Muzzle velocity: 380-520 m/s
Muzzle energy: 730-1090 J
.38 Special:
Muzzle velocity: 270-350 m/s
Muzzle energy: 305-450 J

Just as the .357 Magnum is derived from the .38 Special by lengthening the casing, the .38 Special is derived from the .38 Long Colt, which itself comes from the .38 Short Colt.

From left: .38 Short Colt, .38 Long Colt, .38 Special, .357 Magnum

.45 Automatic Colt Pistol (.45 ACP)

The American 11.43 × 23 mm pistol cartridge known as the .45 ACP was designed by John Moses Browning in 1904 and introduced into service in 1907. It has been the standard American military cartridge since 1911, after winning the competition for a sidearm by the Colt M1911 pistol, for which it was dedicated. The new ammunition quickly became popular in both Americas. The .45 ACP cartridge has a lower muzzle velocity than the 9 × 19 mm cartridge, making it better suited for suppressed firearms, and full metal jacket bullets in the 11.43 mm caliber have greater stopping power than 9 mm bullets.

Sample Data
Bullet weight: 6 - 15 g
Muzzle velocity: 260 - 330 m/s
Muzzle energy: 477 - 702 J

6.35 × 15.5 mm Browning (.25 ACP)

This pocket pistol cartridge, designed for use in pocket-sized semi-automatic pistols, is a simple centerfire cartridge introduced by John Browning in 1905 along with the Fabrique Nationale M1905 pistol. The .25 ACP cartridge is used in light, compact firearms. It has a relatively short range and low power, placing it in the same class as the rimfire .22 LR cartridge, but with a much higher cost, which makes it less popular compared to .22 LR.

Although the .22 LR is slightly more powerful when fired from the longer barrels of rifles, some consider the .25 ACP to be a better choice for personal defense handguns due to its centerfire design, which is inherently more reliable than the rimfire design.

Sample Data
Bullet weight: 3.20 - 3.25 g
Muzzle velocity: 230 - 245 m/s
Muzzle energy: 85 - 95 J

9x19 Parabellum

Parabellum 9×19mm (also known as 9mm Parabellum or 9mm Luger) is a rimless, conical cartridge designed for firearms. Originally designed by Austrian firearms designer Georg Luger in 1902, it is widely regarded as the most popular cartridge for pistols and submachine guns due to its low cost and wide availability. It is the standard cartridge for NATO forces as well as in many countries outside NATO.

The 9×19mm cartridge is great for distance or self-defense. It has enough power to penetrate well at close range while still being easy to shoot with low recoil.

Sample Data
Bullet weight: 6.8 - 8 g
Muzzle velocity: 305 - 420 m/s
Muzzle energy: 584 J

9×18mm Makarow

The 9×18mm Makarow cartridge (designated by CIP as 9mm Makarow, often also referred to as 9×18mm PM) is a Soviet cartridge for pistols and submachine guns. In the second half of the 20th century, it was the standard cartridge for Warsaw Pact military pistols, similar to the 9×19mm Parabellum used in NATO and Western forces. The 9×18mm cartridge was designed by Boris Semin in 1946, and a year later, Nikolai Fyodorovich Makarov designed the Makarov PM pistol based on this ammunition. In 1951, both the Makarov pistol and cartridge were adopted by the Soviet Army, and from then on, the cartridge became commonly known as the Makarow (though this is not its official designation). The cartridge was widespread throughout the Warsaw Pact, but after its dissolution, it gradually began to be phased out. However, this cartridge is gaining popularity in the civilian market (especially in the USA) due to its fairly high muzzle energy.

Sample Data
Bullet weight: 6.1 g
Muzzle velocity: 310 – 340 m/s
Muzzle energy: 303 J

9×18 mm Police

The 9×18mm Police cartridge was developed in the early 1970s in West Germany and temporarily introduced for the German police, specifically for the Walther PP Super pistol. It originated from pre-war work on the 9×18mm Ultra cartridge, whose development was then halted. Over time, the German police ultimately opted for the stronger 9×19mm Luger ammunition, and the 9×18 Police was soon forgotten. The cartridge was made available to the civilian market in 1975 but never gained lasting popularity. Despite having similar markings to the 9×18mm Makarow, it is not interchangeable with it.

Sample Data
Bullet weight: 6.1 - 7.38 g
Muzzle velocity: 312 - 360 m/s
Muzzle energy: 275-324 J

9x17 Short Browning (.380 ACP)

Developed in the USA by John Browning to improve the effectiveness of the Colt M1903 pistol, this cartridge was first introduced in 1908 with the Colt M1908 pistol and in Europe around 1912 with another of Browning's designs, the FN Model 1910 pistol. This cartridge is available in a wide range of loads, from military full metal jacket rounds to more popular self-defense and police loads with hollow-point projectiles.

Sample Data
Bullet weight: 5.50 - 6.15 g
Muzzle velocity: 305 - 335 m/s
Muzzle energy: 256 - 328 J

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