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The Most Common Bullet Sizes and What They’re Good For

Ammunition is the core of any firearm, light weapon, or artillery piece. Every handgun, rifle, and shotgun is simply a launching mechanism. These weapons allow you to use a controlled explosion to propel and direct a bullet or other projectile toward a target. When you’re selecting a firearm, the ammunition determines the application.

Bullet Diameter and Weight

Caliber refers to the diameter of the firearm barrel or an approximation of the bullet diameter. Caliber may be expressed in hundredths or thousandths of an inch (e.g., .38 Special, .270 Winchester) or millimeters (e.g., 9mm, 7.62×51mm NATO).

In metric designations in which there are two numbers separated by a multiplication symbol, the first number is bullet diameter and the second is the length of the cartridge case. You may also see letters, such as R and SR. These indicate the type of cartridge case (i.e., rimmed and semi-rimmed).

Bullet weight is measured in either grains (gr) in the U.S. or grams (g) in Europe. For example, typical bullet weights for the 9mm cartridge are 115, 124, and 147 grains.

Cartridge Components

Ammunition is sometimes referred to collectively as bullets, but the bullet is only one component. A single unit of small-arms ammunition is called a cartridge or round, and generally comprises a total of four components:

Bullet

The bullet is the projectile that leaves the muzzle and inflicts damage to the target. When the propellant charge is ignited, it forces the bullet out of the cartridge case, and into and through the bore (the inside of the barrel.) Bullet design is a complex field. The shape, construction, composition, and weight all affect how the bullet flies through the air and how it behaves when it strikes the intended target.

Propellant

The propellant charge provides the propulsive force for the projectile when ignited. From the 10th to the late 19th century, black powder was the primary propellant in small-arms ammunition, consisting of carbon, sulfur, and saltpeter (potassium nitrate). In 1884, Paul Vieille, a French chemist, invented the first practical smokeless propellant based on nitrocellulose.

Smokeless powders offer increased energy density compared with black powder, produce fewer solid combustion products, and burn more cleanly. Regardless of the type, propellants are low explosives or deflagrants, burning instead of detonating.

Primer

The purpose of the primer is to ignite the propellant. In centerfire ammunition, the primer is a metallic cup containing an impact-sensitive primary explosive. When the firing pin strikes the primer, it compresses the priming compound against an anvil, causing it to detonate. On detonating, the primer sends burning particles through the flash hole in the cartridge case and into the powder charge, initiating the firing cycle.

Cartridge case

The cartridge case is one of the most distinguishing characteristics of modern metallic ammunition. In use for more than 150 years, the cartridge case serves several purposes. First, it holds the other components together in an impact- and weather-resistant package for easy storage and loading. Second, it seals the breech on firing, maintaining gas pressure in the bore to drive the bullet. Third, in semi-automatic and fully automatic actions, it acts as a heat sink.

Ammo Types

The following are some of the most common bullet types in use today.

Full Metal Jacket

A full metal jacket is a bullet consisting of a core and a jacket. The core is typically composed of lead or a lead alloy. The jacket, which encloses the core, is copper, brass, gilding metal, mild steel, or some other material. Before the advent of smokeless powder, exposed lead bullets were commonplace in rifles and handguns.

However, as muzzle velocities increased due to smokeless powder’s increased energy density, the need for a protective barrier between the lead and the barrel rifling became obvious. The jacket’s purpose is to prevent the core from melting due to friction and the temperature of the burning propellant, prevent the deposit of lead fouling in the bore, and increase the bullet’s resistance to deformation on impact with the target. Most FMJ handgun bullets are round- and flat-nosed.

FMJ or ball ammunition is still routinely used in infantry small arms, both rifles, and handguns. However, in a civilian context, FMJ ammunition is mostly relegated to target shooting and range practice roles.

Total Metal Jacket

A total metal jacket is similar to a full metal jacket except that the jacket encloses the base. In FMJ ammunition, the burning propellant can vaporize the lead of the exposed projectile base. TMJ ammunition avoids this, reducing indoor air pollution.

Jacketed Hollow Point (JHP)

A jacketed hollow point is a projectile with a concave nose designed to expand inside the target. The target medium enters the nose cavity, and the rise in pressure causes the bullet to mushroom. As the frontal surface area and effective diameter of the bullet increase, it transfers kinetic energy more rapidly. The result is reduced penetration, compared with an FMJ, and an increase in the volume of the temporary wound cavity. JHP bullets are generally used for defensive and anti-personnel applications.

Jacketed Soft Point

Jacketed soft-point bullets are common in hunting rifle cartridges. The JSP is a hybrid design designed to achieve a balance between expansion and penetration. The soft nose promotes more expansion than the hard tip of a full metal jacket. The convex tip, however, is more penetrative than a hollow point.

Wadcutter

The wadcutter is a bullet designed to be used in revolvers. Consisting of a flat-nosed, cylindrical bullet with a sharp shoulder, the wadcutter is designed primarily for target shooting. In formal matches, scoring requires precise measurement of bullet holes in paper targets. The wadcutter’s flat nose and sharp shoulder cut perfectly circular holes in paper, whereas round-nosed bullets cut more jagged holes.

Most wadcutter loads are low pressure. Outside of the target range, the wadcutter has some practical use as a substitute for JHP bullets in snub-nosed revolvers. If the short barrel would not generate sufficient muzzle velocities for a JHP to expand, a wadcutter will crush more tissue.

Spitzer Boat Tail

While many rifle bullets are FMJ, spitzer refers to a design where the bullet tapers toward a point. A boat tail is a tapered base designed to reduce air resistance by increasing the aerodynamic efficiency of the projectile, increasing accuracy and effective range.

Ballistic Tip

A ballistic tip is a jacketed hollow-point bullet with a plastic insert in the nose cavity. The purpose of the insert is to create a more aerodynamic profile, thereby reducing air resistance (drag) in flight. In lever-action rifles fed from tubular magazines, the ballistic tip allows the shooter to load spitzer-shaped projectiles into the magazine without the risk of causing a catastrophic failure.

Centerfire vs. Rimfire

Modern cartridges are divided into two categories: centerfire and rimfire. In centerfire ammunition, the primer is a separate, self-contained component centrally located in the cartridge case head. When detonated, the shooter uses a depriming tool to remove the spent primer from the primer pocket, preparing the cartridge for reloading.

In rimfire ammunition, the priming compound is located in the rim of the cartridge case. When the firing pin strikes the case rim, it deforms it, compressing the priming compound against the opposite side of the rim.

Centerfire ammunition is generally reloadable. The shooter can reuse spent cartridge casings, replacing the bullets, powder charges, and primers. In rimfire ammunition, reloading is more difficult because the priming compound is not contained in a separate component.

Common Handgun Calibers

Handguns are relatively lightweight, short-barreled, portable firearms designed to be used with one or two hands. Common handgun cartridges include the following:

.22 Long Rifle

A product of the 19th century, the .22 Long Rifle is probably the most popular handgun and rifle cartridge globally. Lightweight, inexpensive, compact, relatively quiet, and producing a low recoil impulse, the .22 LR is one of the best rounds for teaching new shooters the fundamentals of marksmanship, recreational target shooting, and hunting varmints (e.g., squirrels, rabbits) for the pot. It’s also a superb choice for youngsters, as .22-caliber rifles tend to be light and handy.

.380 ACP

Introduced in 1908 in the Colt Model 1908 Pocket Hammerless, the .380 ACP cartridge, also known as the 9mm Short and 9×17mm Browning, is primarily designed for self-defense in compact, concealable handguns. Although there are lighter centerfire calibers, the .380 ACP is widely regarded as the minimum caliber suitable for a CCW (concealed-carry weapon).

9mm Luger

The 9mm Luger cartridge, also called the 9×19mm Parabellum, is the world’s most popular centerfire semi-automatic pistol and submachine-gun cartridge. Georg Luger introduced the eponymous 9mm Luger cartridge to the British Small Arms Committee in 1902 and Springfield Armory in 1903.

Highly versatile, you can find both pistols and rifles chambered with this lightweight, compact and widely available cartridge. Once maligned for its apparent lack of stopping power, the 9mm is ideal for defense when combined with reliably expanding ammunition.

.38 Special

Smith & Wesson introduced the .38 Special cartridge in 1898 to provide superior ballistic performance to the .38 Long Colt. A revolver cartridge, the .38 Special was once the standard caliber among police officers.

Although the .38 Special has been largely supplanted by .380-caliber and 9mm semi-automatic pistols, the cartridge continues to be popular in service-length revolvers for target shooting and snub-nosed revolvers for concealed carry due to its low recoil and variety of bullet designs. Despite its name, it uses .358 caliber bullets.

.357 Magnum

Following a series of improvements to the .38 Special cartridge, such as the .38/44 Heavy Duty, the .357 Magnum appeared on the scene in 1935. Introduced in the Smith & Wesson Registered Magnum, later the Model 27, the .357 Magnum is a potent handgun cartridge suitable for self-defense, law enforcement, and hunting.

Using a lengthened .38 Special cartridge, the .357 Magnum cannot be fired in .38-caliber revolvers for safety reasons, as the difference in chamber pressure is significant. You can fire .38 Special cartridges in .357 Magnum revolvers, however.

.40 S&W

Introduced in 1990, the .40 S&W cartridge is a cooperative effort between Smith & Wesson and Winchester. The FBI had adopted the Smith & Wesson Model 1076 chambered in 10mm Auto. The .40 S&W was designed to replicate the service ballistics of the reduced-pressure 10mm FBI load in a cartridge with a shorter case, allowing it to be fired in medium-framed handguns.

Although Smith & Wesson had developed a semi-automatic pistol for this caliber, Glock released its full-size and compact handguns (the G22 and G23) in the new caliber first.

.45 ACP

During the Philippine–American War, the U.S. Army Ordnance Office was receiving field reports that the .38 Long Colt was not powerful enough to reliably stop charging Moro juramentados — swordsmen — who were proving to be a formidable enemy.

In 1904, following the famous Thompson–LaGarde tests, Colonel LaGarde wrote that for a military pistol or revolver to be effective, it should have a caliber “not less than .45.” The result was the .45 ACP, developed by Colt’s technical staff and Winchester in 1905.

The .45 ACP cartridge, also known as the .45 Auto, delivers a 185-, 200-, or 230-grain bullet at subsonic muzzle velocities when loaded to standard pressures. Big-bore aficionados prize the .45 ACP for its stopping power. The .45 ACP is closely associated with the famous M1911 pistol and its variants. Today, the .45 ACP continues to be a popular round for self-defense and competitive target shooting.

Rifle Cartridges

Rifles are shoulder weapons with rifled barrels designed to fire comparatively high-velocity cartridges for infantry service, hunting, self-defense, and competitive shooting. Common rifle calibers include the following:

.223 Remington/5.56×45mm NATO

The commercial .223 Remington and military 5.56mm cartridges are dimensionally identical and only differ in chamber pressure. As a rule, 5.56mm rifles can chamber .223 rounds; however, the reverse is considered unsafe. Once a controversial cartridge, the .223/5.56mm is effective in light, compact arms for various purposes. In the context of home defense, the short, handy carbines that fire this round are highly maneuverable in confined spaces, recoil moderately, and are acceptably powerful at close range.

.308 Winchester/7.62×51mm NATO

Designed by Frankford Arsenal, Winchester introduced the experimental T65 cartridge to the commercial market in 1952 as the .308 Winchester. Two years later, NATO would adopt the experimental T65E5 cartridge as the 7.62×51mm NATO. The purpose of the new round was to replicate the service ballistics of the .30-06 Springfield in a cartridge with a shorter case.

A shorter cartridge allows for shorter rifle actions, reducing the overall length and weight of infantry weapons. It would also allow the soldier to carry more ammunition, as the cartridge was lighter in weight.

The commercial and military variants are highly versatile, reasonably powerful, and accurate, depending on the load. Used for long-range competitive target shooting, hunting, law enforcement, and military sniping, the .308/7.62mm is available in every action type.

.300 Blackout

Based on a .221 Fireball cartridge necked down to .30 caliber, the .300 Blackout is an intermediate cartridge designed for use in AR-15-pattern weapons. When supersonic, the .300 Blackout is ballistically comparable to the 7.62×39mm Soviet. As the .300 Blackout is compatible with .223/5.56mm bolts and magazines, converting your rifle from one to another requires only a barrel change.

.30-06 Springfield

The .30-06 cartridge, adopted as an infantry rifle caliber in 1906, is still used today as a versatile hunting cartridge, suitable for everything from whitetail deer to big game. As the .30-06 has a longer case neck than the .308, it can accept bullets up to 220 grains in weight for extra penetration. Outside of bolt-action hunting rifles, the .30-06 is associated with the M1 Garand and military weapons collectors.

Shotgun Shells

common bullet sizes

Shotguns are typically shoulder weapons with smoothbore or rifled barrels designed to fire shotgun cartridges. The most common shotgun shell size is 12 gauge, offering both versatility and availability to the shotgunner. For those who are more sensitive to recoil, however, a 20-gauge shotgun will also suffice.

Gauge is the equivalent of caliber in the context of shotgun ammunition, referring to the number of lead balls of a particular size that are needed to equal one pound. In a 12-gauge shotgun, for example, twelve lead balls of .729 caliber are necessary to achieve that weight.

Shotgun shells are available in a variety of different loads. Birdshot is ideal for hunting waterfowl and upland birds and shooting skeet. Buckshot is useful for home defense, tactical applications, and deer hunting.

Slugs, whether rifled or sabot, provide increased range and penetrating power compared with shot pellets. As a result, they’re useful for defense against dangerous fauna and for shooting game animals at longer distances.

Find the Best Range of Ammo at IFA Tactical

At IFA Tactical, we understand that ammunition plays a vital role in firearms and shooting sports. It’s the bullet or shot pellets that strike the target — the gun is the delivery system. If you’d like to discuss your shooting interests with us, give us a call at (586) 275-2176. We can help you select the caliber and ammo that suit your preferred shooting activity, whether self-defense, hunting, target shooting, or competition.