[The Definitive Guide] Bullets: Sizes, Calibers, and Types

Bullets: Sizes, Calibers, And Types

Ammo is Important, Are you agree with me?

But there’s a lot of size, types on the market.

Each type of bullet had a specific function, such as for concealed carry , target shooting, sefl-defense, and even hunting.

Keep reading!

You’ll have more information to make the right choice.

Parts of a Bullet Cartridge

Parts of a Bullet Cartridge

All ammunition is made of some basic components;

  1. The projectile that is launched is called the bullet (multiple projectiles, such as from a shotgun, are referred to collectively as shot)
  2. The container that holds all of the other components is called the cartridge, the case, or sometimes the shell.
  3. The gun powder is what gets ignited to propel the bullet
  4. The primer is what initially sets off the gunpowder to start the reaction

Rimfire vs Centerfire

Today, there are two common types of ammunition: centerfire and rimfire. The words mean what they sound like.

In centerfire ammunition, the primer is located in the center of the cartridge. It is typically a removable “cup” that is filled with primer compound and then pressed into the back of the cartridge.

The firing pin strikes this cup, igniting the primer compound. This is the way the vast majority of firearms work today.

The other type is rimfire. Instead of striking the center of the cartridge, rimfire guns work by striking and crushing the rim of the cartridge.


Instead of a primer cup, rimfire cartridges have a primer paste that is loaded inside the cartridge, around the rim.

When the rim is suddenly smashed close, the energy ignites the primer which sets off the whole round.

Centerfire cartridges are much more common, controllable, and reliable.

A shooter can also take the fired case from a centerfire cartridge and reload it with new components to shoot again (called re-loading or re-manufacturing.)

On the other hand, rimfire ammunition is much cheaper. It is, however, less reliable and cannot be reloaded by the shooter.

The most common rimfire cartridges today are all low powered, small calliber rounds – such as .22 Long rifle, .17 HMR, and .22 WMR.

Most Common Pistol Calibers

Handgun Ammunition

Pistols are defined as firearms which are carried in and fired from the hand. They are designed to be portable and reliable. Pistols are less accurate and less powerful than rifles.

As a trade-off, they are designed to be very maneuverable and to be controllable to the shooter.

There are mainly two types of pistols that we will be concerned with: revolvers and semi-automatics.

These are what are included in the average person’s definition of a “pistol”, so they are most relevant.

The Semi-automatic pistol has been around for roughly 120 years, in which time it has become popular for the capacity of firepower, low recoil, and low physical strength required.

Although they are favored for this reason, they cannot use cartridges that are as powerful as revolvers.

There are a number of popular semi-automatic handgun cartridges, for different uses.

1 Small Concealed Carry Pistols – .25, .32, and .380 ACP

Since pistols were invented, it was realized that they made perfect self-defense items because they could fit in inconspicuous places such as a man’s pocket.

Some of the very first of these pistols were chambered in very small cartridges, designed to fit the small size of the pistol.

These were the .25, .32, and .380 ACP.

Of these today, the .380 is the only one that is still commonly considered acceptable for self defense.

These rounds are small, relatively quiet, and have low recoil. On the downside, however, they have very low power.

380 ACP Semiauto for Self-Defense
.380 ACP Semiauto for Self-Defense

The most powerful of these is the .380 ACP, which is still commonly used for very small concealed carry pistols.

The .25 and .32 ACP have fallen out of popularity because advancements in manufacturing technology have allowed the creation of .380 handguns that are incredibly small.

Another problem with these cartridges is that they lack velocity to work properly with hollow points.

Solid round nose centerfire and rimfire are the only ones that work reliably in these calibers, which makes them less suitable for self-defense.

Unlike more powerful calibers, the bullet stays the same size and is only capable of poking a relatively very small hole.

2 Standard Automatic Calibers – 9mm, .40 and .45

The 9mm Luger (also called 9mm Parabellum and 9X19mm NATO) and the .45 ACP have both been in widespread use since their introduction over 100 years ago.

They have become standards for use in semi-automatic duty pistols and have since gained popularity for use in target shooting, home defense, and concealed carry.

The 9mm and .45 represent two opposing schools of thoughts on the proper caliber for a handgun.

On the one hand, the 9mm Luger is a smaller, faster projectile (usually between 115-147 grains) with lower recoil and a higher magazine capacity.

On the other hand, the .45 ACP is a heavy (185-230 grain), slow moving projectile with higher recoil and a lower capacity.

In the middle, there is the .40 Smith & Wesson that claims to have the benefits of both – higher stopping power than the 9mm with less recoil and more capacity than the .45 ACP.

Left to right: 9mm Luger, .40 S&W, .45 Auto

There is lots of argument about which firearm is the most effective for self-defense use, but they all enjoy massive popularity for both defensive and sport uses and any of them will make for a valid choice.

In particular, the effectiveness of enhanced bullet technology such as bonded hollow-point bullets make them all excellent performers for defensive applications.

Read more:

3 Standard Revolver Calibers – .38 Special/ .357 Magnum

.38 Special and .357 Magnum

The .38 cartridge has been around for almost as long as the revolver has, and the .38 Special took over for its versatility and capability.

The traditional bullet is a 158 grain lead round nose or wad-cutter bullet, which is known to create effective expansion even at low capacity.

The .38 Special is a capable performer in a revolver, with decent ballistics and stopping power even in short barrels.

The recoil is comfortable enough that even new shooters can handle it, and increased performance +P loads add extra power.

It is known to be somewhat snappy in small, short-barreled guns.

The .357 Magnum was created to take the .38 special and drive it to extra power.

Known for creating snappy recoil and impressive flash and noise, the .357 magnum has a reputation for reliable power.

In fact, it has been shown to be one of the most effective man-stopping cartridges shot for shot in police and self-defense use.

It is also known to be an effective round for a hunting or woods revolver, but is on the weaker side for this (we’ll talk more about hunting calibers later).

The .357 Magnum and .38 Special share some interchangeability.

Any gun which accepts .357 magnum can safely use the softer .38 special, but not the other way around.

.38 Special is commonly used in .357 firearms for target shooting and training, since it is both cheaper and easier on the hands.

4 High Powered Specialty Rounds – 10mm, .41 and .44 Magnum, and Big-Bore Revolver Cartridges

Some cartridges are higher-powered and more specialized, and can be somewhat intimidating to the inexperienced shooter.

Some are used for self-defense (most notably the 10mm Auto), but they are generally used for defense from wild animals as well as big game hunting.

The 10mm Auto pushes the limits of what can be packed into a standard semi-automatic handgun.

More powerful than the .45 ACP, it pushes heavy 200+ grain cartridges at well over 1,000 FPS.

It is sometimes carried for self-defense (Glock even makes a compact version for concealed carry) but is considered by many to be even too powerful for this use.

It has a reputation for stopping not only man, but charging beasts such as hogs.

In fact, Danish special forces are equipped with 10mm handguns for defense against polar bears and other large wild animals.

In revolvers, we have the .41 and .44 Magnum cartridges, which are known for their incredible power.

The Model 29 Smith & Wesson in .44 Magnum was famously introduced in the movie Dirty Harry as “The Most Powerful Handgun In the World”.

Elmer Keither, handgun aficionado and inventor of the .44 magnum cartridge, recorded killing deer at 200 yards with a .44 magnum revolver equipped with a scope.

Finally, there is an additional class of big-bore revolvers that belong only in the hands of very experienced shooters with special requirements.

These include the .454 Casull, .460 VXR, and .500 Smith & Wesson.

These firearms are known as “hand cannons” which require exceptional control to handle and fire accurately.

By way of example, the .500 Smith & Wesson can shoot a nearly 400 grain bullet at over 1,500 feet per second (almost twice the weight and speed of the .45 ACP).

Such big bore revolvers are expensive to buy and expensive to shoot. They best fit the needs of a specialized group of outdoor sportsmen.

They may be used for big game hunting where massive stopping power and capable range are required, but a rifle or shotgun would be too cumbersome or heavy.

Fitting all that power into a handgun makes a hunting firearm that can be easily carried.

They are also carried in parts of the wilderness where encounters with grizzly bears, moose, and other large and enraged animals may need to be stopped immediately.

Most Common Rifle Calibers

1 Common Military Calibers – .223/5.56 NATO and 7.62X39mm

Especially popular in America are calibers which were originally designed or widely adapted for military use.

The .223 Remington was originally a sporting caliber and is suitable for bolt action use, but alongside with the 5.56mm NATO is very commonly used in semi-automatic “tactical” rifles.

It fires a small, .22 caliber bullet at speeds sometimes exceeding 3,000 FPS.

The recoil produced is very low, but the noise is very loud due to the high pressure and small exit diameter of the gunpowder.

The high speed and lightweight of the bullet can make for a very deadly tumbling effect.

But the lightweight .223 bullet is considered inhumane for hunting in many states and some people may feel it is too small to effectively be used for self-defense.

The 7.62X39mm cartridge has been famously used in a number of firearm designs such as the SKS and AK-47.

It fires a .30 caliber bullet with stopping power and ballistics similar to that of the .30-30 Winchester hunting round.

It has a shorter effective range than the 5.56mm cartridge (its trajectory is often described as a “rainbow”), but it is popular for its “punch” at short distances.

It is also one of the cheapest calibers around, and most rifles designed to shoot 7.62X39mm NATO will cycle the cheapest steel ammo with ease.

2 Lever Action Cartridges – .30-30 and .45-70

Lever actions are iconically American, and are still present in many American homes and hunting cabins around the U.S.

They are generally inexpensive and are popular because they are lightweight, easy to carry, and point very quickly at animals in tight brush.

The .30-30 Winchester was at one point claimed to have killed more deer than any other cartridge in America, a statement which might still hold some merit.

It fires a .30 caliber projectile at moderate speeds of around 2,500 Feet per second.

The heavy, round-nose bullets have poor ballistics, but .30-30 lever action rifles are typically considered to be 200 yard rifles anyways.

.30-30 recoil is moderate and considered very manageable, and the cartridge is known to be easily capable of killing medium game such as deer, hogs, and even small bears.

The .45-70 is a much larger cartridge with a storied history.

First used on the American frontier, the .45-70 had power capable of harvesting animals such as buffalo.

Although ballistics are generally poor by modern standards, 19th century marksmen are recorded as target shooting as far as 1,000 yards with it!

The .45-70 has considerable recoil, but that is accepted for its use as a big game stopping rifle.

The .45-70 is still trusted to operate reliably in some of the harshest climates in America, to stop some of the biggest animals.

3 Common Hunting Rifle Cartridges

There are simply too many hunting rifle cartridges to name all of them, but instead we can cover some of the most common ones and their different uses.


.243 Winchester and 7mm-08

Both cartridges based off of the .308 Winchester Cartridge, they use the same case with smaller bullets (6mm and 7mm, respectively).

What these cartridges offer is lower recoil than the .308 Winchester, and longer bullets that suffer less from the effects of bullet drop and wind drift at long ranges.

Therefore, they are common and well-liked for children’s hunting rifles as well as for general use hunting rifles where the animals have a thinner skin.

.308 Winchester – One of the most common rounds in America.

Introduced in the .50s, it has become popular due to both its commercial success and widespread military adoption as the 7.62X51mm NATO.

The .308 Winchester is a very popular general use cartridge which has very capable stopping power on medium to large sized game, and is known to be routinely capable of shots up to 1,000 yards.

It’s hard to go wrong with a .308 Winchester for a rifle to handle all situations.

.270 and .30-06

The .30-06 cartridge saw the US through some of its most important wars. It is a potent cartridge, used in 1,000 yard rifle cartridge as well as large and dangerous game hunting in the U.S.

It is very similar to the .308 Winchester, which was developed to provide the capabilities of the .30-06 in a shorter case. It is a very well-favored hunting cartridge, one of the “American Classics”.

The .270 Winchester is a .30-06 necked down to use a .27 caliber bullet instead of 30 caliber.

This results in slightly less recoil and better long range ballistics, at the cost of a smaller overall bullet.

Nonetheless, with its high velocity and today’s bullet technology, it is an incredibly capable cartridge.

Famed hunter Jack O’Connor said that there is no animal in North America which a .270 cannot cleanly kill.

Shotgun Cartridges


Shotgun cartridges are among some of the most ubiquitous but least understood cartridges in America.

Because of their outdated naming convention, it’s not clearly understood what the numbers in shotgun cartridges mean.

Not to worry, though, as we’ll break it down clearly for you.

The first thing to know is that a shotshell cartridge can contain several types of projectiles.

When they contain one solid projectile, like the other ammunition discussed, this projectile is referred to as a slug.

Slugs contain massive power in a short distance, but also can cause very objectionable recoil.

They are used for big game hunting, stopping aggressive animals, and in tactical situations in roles as extreme as shooting into engine blocks.

When there are multiple pellets in one shell, we refer to this as shot.

Birdshot Vs Buckshot

Modern shotshells typically come in two varieties: birdshot and buckshot. The names give clues as to what they mean and what they were designed for.


Birdshot contains many (even hundreds) of very tiny pellets which are designed to disperse across a short distance and to kill flying birds.

Birdshot is typically numbered, so that a higher number means a smaller shot.

For instance, #9 shot is typically the smallest available while other uses might call for #4 or #2 birdshot.

Birdshot loses energy very quickly over a distance and has poor penetration. It is a poor choice for defensive or tactical situations.

Buckshot is larger and is intended for larger animals (as the name implies). It is commonly used for deer, hogs, and even coyotes.

In addition, it is one of the most popular choices for defense and tactical uses.

Buckshot is frequently used by police officers and other armed professionals such as correctional officers due to its immense stopping power and spread over distance.

Buckshot also uses a numbering system but is not on the same scale as birdshot.

For instance, #4 buckshot is much larger than #4 birdshot. #4 is the smallest common size, while larger sizes range from #0 to #000 (more zeroes meaning fewer, larger shots).

Another confusing aspect of shotgun ammo is the gauge. We may have heard of 12 and 20 gauge, but what does it mean? It’s not clear like 9mm or .223, both of which are direct measurements of the diameter of the bullet.

Shotgun Ammo Sizes

Shotgun bore gauge size is determined by the weight of a perfectly round lead ball that matches the size of the bore.

For instance, a 12 gauge shotgun means that a round lead ball perfectly sized to a 12 gauge bore will weigh 1/12 of a pound (1.33 ounces), while a 20 gauge round lead ball would weigh 1/20 of a pound (0.8 ounces).

Let’s look at common shotgun ammo sizes:


.410 ammo is the smallest shotgun ammo commonly available today. It uses a very small bore and a small diameter shell that holds little powder and pellets.

.410 is commonly used for a child’s first shotgun due to the very low recoil and the low power.

.410 is also commonly used for hunting small game such as squirrels, rabbits, grouse, and occasionally dove.

It has recently become more popular after being chambered in several revolvers such as the Taurus Judge and Smith & Wesson Governor.

With this, more powerful defensive ammo has also been developed.

28 and 24 gauge

Falling somewhere in between, 28 and 24 gauge shotguns are still considered small-bore but carry more shot than a .410.

They are less common today and are most frequently used by sport shooters and hunters who have a specialized preference.

20 gauge

Today’s go-to caliber for all around use, the 20 Gauge packs a moderate amount of shot with a moderate amount of recoil.

The cartridge is not so powerful that it cannot be used by women and children, but is capable of being used in a number of hunting situations.

It is often used for dove and upland birds while hunting, as well as being popular for skeet and trap shooters.

The recoil is lower than 12 gauge so it is comfortable to shoot for a longer period of time.

20 gauge is also becoming more popular in tactical and home-defense firearms, as it offers a shotgun option for people who cannot tolerate the recoil of a 12 gauge.

Because of this, 20 gauge ammo can be found in birdshot, buckshot, and slugs.

12 gauge

Today’s popular idea of a shotgun usually consists of it being 12 gauge. 12 gauge is one of the most popular and ubiquitous rounds in history.

Loaded with anything from #9 shot to copper plated sabot slugs, the 12 gauge is highly versatile and capable of use in almost any role.

It is popular in hunting just about any time of game which can be hunted with a shotgun, and is probably one of the most kept firearms in the US for home defense due to its high power and ease of use.

It is also very commonly used in skeet and trap shooting as well as more active shooting sports such as 3 Gun (which often require a 12 gauge to be used in many categories).

12 gauge does come at a cost, though, as the recoil can be extreme and objectionable to some shooters, especially in lightweight hunting guns.

10 gauge

If 12 gauge is big and bad, 10 gauge is bigger and badder. 10 gauge is still available today, but typically by special request in many firearms models.

10 gauge has a limited number of uses, but in these it excels. The main idea behind a 10 gauge shotgun is to pack even more shot than a 12 gauge, increasing hit probability.

For this reason, it’s most popular for upland ducks and geese, which fly at a high altitude and also require larger shot to kill than other birds.

More, heavier shot greatly increases your chance of a killing shot on these animals, which of course every hunter wants.

It is relatively rare and expensive, with heavy recoil, but has its benefits for those specialized hunters who have a use for it.


Navigating all of the firearm caliber choices can be confusing and overwhelming, but it all comes down to picking the right one for your need.

Hopefully, after reading this guide, you’ll have more information to make the right choice for you. Until next time, happy shooting!