Bullet Sizes: Bullet Caliber Charts for Size Comparison

In the initial times, after the discovery of gunpowder in ancient China, gun powder was principally used as the fuel for bombs and cannons. Nations in Asia like China, India, Mongolia developed small-sized cannons that could be used by the infantry. This type of cannon probably led to the development of the concept of firearms. The hand-held cannons were followed by flintlock rifles and guns. The modern rifles were developed as a result of the development of bullets and cartridges. This development revolutionized the battlefield forever. Today billions or rather countless 'rounds' of ammunition are manufactured every year, out of which a large percentage is used in battles, encounters, practice sessions and hunting.

The concepts of caliber and size are used to distinguish 'rounds' or bullets. A projectile which is fired from a gun, is more commonly known as a bullet. It is actually a metallic case that is filled with ammunition. The diameter of the cartridge is used to determine the caliber of the bullet. The caliber of the bullet is expressed in terms of dimensions of the cartridge.

There are three important terminologies that one needs to understand, namely gun caliber, bullet diameter and rifle cartridge dimensions. There three are totally different entities:

1. A gun's principle mechanics involves the barrel, firing chamber and the firing pin. The rifle cartridge enters the firing chamber and upon the pull of the trigger, it is hit by a firing pin, causing the propellant within it to explode.
2. This explosion causes the bullet to shoot out of the cartridge, through the firing chamber and barrel and towards the target. In the mean time the now-empty cartridge exits the gun.
3. Thus to know what kind of bullet one needs to use in the rifle, there are three things that are to we noted. One, the bullet diameter and size, two, the length and diameter of the cartridge and three the gun's caliber.

Within this process, it is important that the gun's caliber and the bullet's caliber be in compliance. That is, the inner diameter of the barrel and the outer diameter of the bullet should have a minute difference. Such a difference ensures a smooth, safe and accurate firing. The following table is an example to the bullet caliber chart for size comparison.

No.	Name of Cartridge	Type	Length	Usage	Bullet Diameter
1	.50 BMG	Rimless and Bottleneck	5.45 in / 138 mm	Machine guns and sniper rifles	0.51 in / 12.95 mm
2	.308 Winchester	Rimless and bottleneck	2.800 in / 71.1 mm	Police sharp shooting and short action rifles	0.308 in / 7.8 mm
3	7.62 x 39 mm	Rimless	2.205 in / 56.00 mm	Common rifles	0.311 in / 7.89 mm
4	5.56 x 45mm NATO	Rimless and bottleneck	2.260 in / 57.40 mm	M16 assault rifles	0.224 in / 5.7 mm
5	.22 LR	Rim fire and straight	0.985 in / 25.0 mm	Pistols and Revolvers	0.222 in / 5.6 mm

Naming Conventions and Denominations

The caliber or diameter can be measured and depicted either with the help of the metric system (mm) or the Imperial system (inches). European and Commonwealth or former Commonwealth nations usually use the metric system. Nations in North America, especially the United States, domestically use the Imperial system. However, to facilitate the functionality and operations with international organizations such as NATO and United Nations Peace Keeping forces, the nations using the Imperial system use the metric system.

• As per the imperial system, the diameter is expressed in 'hundredths of one inch', that is hundred equal divisions of 1 inch. In such cases, if the bullet diameter is noted to be .30 cal, it would mean that it has a diameter of 30 hundredths of 1 inch. It is a common convention to name the bullet at '30 cal'.
• As per the metric system, the bullet has a 7.62 mm diameter. In several military issue rifles, the metric system is widely used. In such a system, the length of the bullet is also denoted. For example, the M4 Carbine uses a 5.56x45mm NATO cartridge. The cartridge diameter is 5.56 mm and the bullet diameter is 5.7 mm.

Explanation of the Bullet Caliber Chart

The cartridge of the bullet acts like a covering for the ammunition inside. After the bullet has been fired, the cartridge is ejected from the gun and a new bullet takes its place. The caliber of the bullet is determined by measuring the diameter of the cartridge, inside the barrel of the gun. The cartridge that is placed inside the gun touches the surface of the gun's barrel from all sides. After cartridge is placed in the firing chamber, the barrel of the gun gets sealed. The only portion that remains unsealed is the bore of the gun through which the bullet leaves the gun. The caliber of the bullet must be a bit smaller than the diameter of the barrel. Bullet caliber chart for size comparison helps the user find the appropriate ammunition, that corresponds to the gun's barrel.

The bullet caliber charts are especially helpful to hunters or the people who practice shooting as a sport. Armed forces or the police forces produce their own ammunition, and hence do not need the charts to determine bullet caliber sizes. Soldiers have an acute knowledge about bullet sizes and bullet caliber charts because, they tend to know the guns that are being used by other military forces as well. Many times, during overseas assignments or missions, soldiers run out of arms and ammunition. Hence, they resort to the arms and ammunition captured, from enemy personnel. Their knowledge about the different types of ammunition comes in handy in such situations. Some of the calibers of the commonly used bullets by military personnel are as follows.

• The .22 bullet size is found in all the bullet comparison charts, military and civilian alike. Some of the prominent examples of the .22 bullets are, BR Remington, Hornet, Winchester Rimfire, Spitfire bullets.
• .416 is a recently developed range of ammunition, that is prominent in sniper rifles. This bullet was developed by Barret fire arms, especially for snipers.
• .44, .50 and .22 are some of the popular bullets that are used in pistols and revolvers.

Bullet sizes and bullet caliber charts are also available in the metric system. While using the metric system, some manufacturers also include the length along with the diameter while stating the caliber of the bullet. One of the prominent example that has been used in the table is 7.62 x 39 mm. In this situation the smaller figure is the diameter of the bullet in millimeters and the bigger figure is the length.

The most important step before purchasing a set of bullets is to assess the caliber of the gun and bullet, and conclude if they are compatible or not. This step is extremely important to maintain the standards of gun safety, and also ensure an accurate hit or rather a bull's eye. A mismatch may result into a very dangerous situation.