When you think of shooting a pistol, you usually think about how to shoot a gun, your stance, or the different parts of your firearm. You what I got it! You think about concealed carry and self defense, but is that it. Depending on your gun knowledge you may or may not think about what caliber you are shooting, but do you truely understand this subject of calibers?

When you read that last statement, did you think about the caliber of the pistol or the ammunition you are using?   

Caliber is the least understood topic that is essential to shooting. I hear people talking about the different handgun caliber sizes all the time, but is size the only thing that matters when determining a caliber?

Naturally Outdoor Methods is going with the ”all in” mentality to simplify this topic for others. However, be warned this topic can get very complicated no matter how much we summarize it. So before buying a gun or holster (like the Alien Gear Holsters Shapeshift 4.0) lets go head first down this rabbit hole.

What Does Caliber ACTUALLY Mean?

Caliber: is basically the terminology used to label a specific model gun that uses a particular round. It is typically determined by the dimensions of either the gun’s barrel or the bullet (not the cartridge). Clear as mud? Okay, let us take a closer look at these two methods:

One: If using the gun’s barrel to determine the caliber, we will use the inner opening( aka bore) of a gun’s barrel from land to land. This will be measured in either fractions of an inch or millimeters.

That is great and all, but what are lands? Have you ever noticed the spiral grooves going down the barrel of your gun? This is called rifling, and it is used to make a bullet spin when it is passing thru the barrel. The areas between the groves are called lands.

In plan terms, if using the gun itself to determine the caliber, you measure the barrel’s narrowest opening.

An example of a gun that uses this method to define its caliber is the British .303, with the land to land area of the barrel measuring .303 inches. The bullet’s diameter is actually closer to .311 inches.

Two: If using the bullet to determine the caliber, you typically use the width of the bullet. These measurements are usually expressed in fractions of an inch or in millimeters as well.

An example of a caliber using this method would be the 0.357 Magnum.

However, calibers are not always determined by these methods. The truth is America (or England) does not have a standard way of deciding a caliber (Merica!!). On the other hand, Europeans do follow a more robust method.

What is the Difference in Pistol Calibers?

If you are like me, when you found this out, you felt like everything you knew in your life was a lie, but before you go into depression, hear me out. Stop trying to look at calibers as if it is a standardization naming method and more of caliber as a way to label a specific cartridge and firearm with certain innate characteristics that separate it from other rounds and guns.

The Variables We Used for Pistol Caliber Comparison

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Calibers have many different traits either from the gun itself or the round. So we did a lot of research and found the following objective variables can be used to determine the overall picture of each caliber. They are:

• Bullets Weight-(grains)
• Velocity- (fps)
• Muzzle energy (ME)- (ft.lbf) ME is also known as kinetic energy, or free recoil. I know mind blown!

You can make an argument for the bullet’s diameter to be used. Yet, per our research, it is not as critical as the variables above. However, it has been added to our best handgun caliber compassion chart. 

Variables We Did Not Use in Our Handgun Calibers Comparison

There are many variables that some would say need to be taken into account when analyzing different calibers. However, we believe these traits are subjective and have decided to leave them out. 

• Stopping Power
  • The more controversial one of them. Stopping power, how many people think this is a critical factor when it comes to calibers? A lot! However, this a very subjective variable that cannot be measured. Why? We are glad you asked!
    • 1. The anatomy of different species. Humans’ anatomy is a lot different from dogs, cats, bears, deers, etc. Something that can stop us with one shot might not stop a bear.  
    • 2. There are also differences in traits in a specific species itself. Think about it a 325 lbs. 6’4″ man, in theory, can take a harder hit than a 5’6″ 150 lbs. man. You then have to think about fight or flight, aka known as adrenaline. We have all heard of people and animals getting supernatural strength when they have adrenaline pumping in their veins. A bullet that should stop somebody or something may not due to adrenaline. Another factor is drugs. Stimulants can make humans, and animals go longer than they usually could 
• Accuracy
  • We can look at accuracy as to how close a shot is from its intended target. Such a simple concept has so many factors affecting it. Some of them are
    • Accuracy of the shooter
    • The design of the bullet
      • For example, a full metal jacket or a hollow point ammo.
  • The design of the gun you are using
    • Length of the barrel
    • Rifling of the gun
      • When a bullet exits a modern firearm, it goes out spinning and acts like a gyroscope that counters outside factors from pushing it off its current path via the Law of Conservation of Angular Momentum
    • What type of sights are you using?
      • Iron sights
        • It is useful for close range but not for long distances. 
      • Scope
        • Scopes are suitable for long-range shooting but make shooting up close very difficult.
• Terminal Performance
  • A method to measure how much damage a bullet will do once it enters soft tissue. A block of 10% gelatin is typically used to simulate soft tissue in this test.
  • A few of the variables that play into a bullet’s terminal performance are velocity, penetrations, and expansion. The last two are both factors of the bullet’s design. Since terminal performance has more to do about the bullet’s design and less to do about the Caliber of the pistol or handgun cartridges, we are omitting this factor. Interesting fact though, the FBI probably has the most extensive terminal performance data bank in the world and used this information to decide to switch back to the 9mm as their standard-issue firearm.
• Recoil
  • In theory, recoil can be measured. How do you ask? Easy you use the Law of Conservation of Momentum that states that for every action, there is an opposite and equal reaction. Somebody, please call my old physics professor up and tell him I actually did listen in class even though my grades didn’t show it. So what factors determine recoil?
  • How “hot” the round is which means the more gun powder you have, the more of a “kick” you will have
  • Size and weight of the bullet. If you look at the chart and graphs below, you can compare the bullet’s size and weight to the ME. 
  • The larger the gun, the more it will absorb recoil once the gun is shot. 
  • The weight of the firearm also plays into this. A a nice, concealed carry polymer pistol will have more recoil than a big revolver.
  • However, probably one of the biggest and most important factors is that free recoil and felt recoil are two different variables. Free recoil (kinetic energy) is the recoil that can be calculated but felt recoil is subjective to the person experiencing it. A big guy will feel less recoil than a small man. Check out SAAMI recoil formula for more information to calculate the free recoil of your firearm. 

Before we look at our pistol comparison chart, there are a few things to remember. Most calibers have many different variations of ammo and firearms. With that in mind, we tried to give you a range of different cartridges for each caliber that you typically would see. We are not saying this chart is all-inclusive, so keep that in mind.  

Also, the listed purposes for each sample is what the majority of people use it for. You may use a specific caliber for a different purpose that is not listed. If you do, please let us know below in the comments. Also, note that semi-auto pistol and revolver calibers are both covered in this chart. 

Note: A common misconception is that a bullet is one unit of ammunition. However, technically bullets are only metal projectile. One unit of ammunition is called a cartridge.  

Now the part you have been waiting for.

The Handgun Caliber Comparison Chart (That Can Be Used as Bullet Calibers Conversion Chart)

(or as some would say our bullet caliber chart). 

There you have it folks! The handgun calibers in order. I know it is a long chart…I spent hours researching and creating it. Our hope is that by seeing and studying the data above, you can start to understand the differences between pistol calibers. Remember this is not a rifle cartridge comparison chart.

To drive caliber concepts home, let’s look at some of the most common handgun calibers used today. Many would argue one of these is the best handgun caliber.

.22 (LR, WRF, WMR, Hornet)

• Typical Bullet Weight Range: 35-55 gr
• Typical Velocity Range: 1138-3060 fps 
• Typical ME Range: 116-765 ft.lbf

.22 calibers are notable as being one of the last remaining commonly-manufactured types of rimfire ammunition, i.e., rounds wherein the powder is set aflame by primer located in the rim of the cartridge. Most common pistol calibers today are “center-fire,” with the primer located on a striking surface at the center of the casing instead.

The rounds themselves differ only in terms of length and powder charge; all fire a small, light projectile most suited for target practice and small game hunting. The .22 has acquired a folkloric reputation for lethality due to its supposed propensity to bounce around inside a target; this has been widely disconfirmed by modern studies of stopping power.

.25 ACP

• Typical Weight Range is: 45-50 gr
• Typical Velocity Range: 760-815 fps 
• Typical Muzzle Energy Range: 64-73 ft.lbf

.32 ACP 

• Typical Bullet Weight Range:  60-71 gr
• Typical Velocity Range: 800-950 fps 
• Typical ME Range: 100-129 ft.lbf

0.25 ACP and 0.32 ACP, the “sub-combat” calibers, occupy a strange space in the world of mainstream handgun ammunition. Both offer a light, short cartridge suitable for an easily-concealed handgun; neither offer particularly impressive ballistics. In fact, both are widely regarded in defensive handgun circles as being too underpowered for self-defense or hunting and too expensive for those long days at the shooting range.

Originally developed during the era of nascent semi-automatic pistols, both rounds were intended for self-defense but have since been supplanted by superior alternatives which offer more mass, velocity, or both. Outside of collectors’ firearms and backup guns, neither cartridge is commonly recommended for everyday use.

.38 Special & .38 Special (+P)

​Note: .38 special is only available in a revolver.  

• Typical Weight Range:  95-158 gr
• Typical Velocity Range:710-1250 fps 
• Typical Muzzle Energy: 132-548 ft.lbf

.357 Magnum

• Typical Bullet Weight Range:  110-180 gr
• Typical Velocity Range: 1080-1500 fps 
• Typical ME Range: 410-644 ft.lbf

The smaller of the two magnums, .357, became one of America’s most popular self-defense calibers when it was retooled from the existing .38 Special cartridge during the 1930s. The .357 magnum and .38 special use similar bullets, but the .357 magnum has more powder in its round (even more than the .38 special +p), that results in increased pressure. Contrary to popular belief, the case of the .357 magnum was not designed to be longer than the .38 special case to hold more gun powder but to prevent people from loading these into .38 special pistol.

The .357 magnum results in higher pressure when fired compared to a .38 special. As a result, .38 special pistol cannot withstand the pressure from a .357 magnum round. A .357 magnum round shot in a .38 special gun would cause a lot of damage to the gun. However, .38 special round can be shot in a .357 magnum pistol due to the .38 special lack of pressure generated when fired compared to the magnum round. Many people use the .38 special in a .357 magnum for target practice. In a nutshell, the .357 magnum is the big brother of the .38 special.

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.44 Special 

• Typical Weight Range:  240-246 gr
• Typical Velocity Range: 750-870 fps 
• Typical Muzzle Energy Range: 300-336 ft.lbf

.44 Magnum

• Typical Bullet Weight Range:  180-240 gr
• Typical Velocity Range: 1350-1600 fps 
• Typical ME Range: 972-1045 ft.lbf

The larger 0.44 Magnum came about two decades after the 0.357 Magnum, and both remain popular for self-defense applications and, to a limited extent, hunting with the 0.44 Magnum. There are carbines chambered for both cartridges, most of which mimic the lever actions of yesteryear modernized for today’s ammo.

 The 0.44 special is the lower powered 0.44 caliber than the .44 magnum that is used mainly for targeting practice and hunting. Due to the higher pressures involved, very few semi-automatic firearms are capable of feeding rounds of the 0.44 Magnum; an exception is the Israeli Military Industries Desert Eagle pistol, of Hollywood fame. Versions of the Desert Eagle exist chambered in 0.357 magnum, 0.44 magnum, and Action Arms’ proprietary 0.50 Action Express magnum round.

.380 ACP & .380 ACP (+P)

• Typical Weight Range:  85-100 gr
• Typical Velocity Range: 900-1150 fps 
• Typical Muzzle Energy Range: 162-294 ft.lbf

9 mm

• Typical Bullet Weight Range:  70-147 gr
• Typical Velocity Range: 950-1650 fps 
• Typical ME Range: 309-423 ft.lbf

The .380 ACP is slightly smaller in diameter than the 9mm. As a result, the .380 ACP gets to be call the smallest of the combat calibers.

With it’s moderate bullet diameter and a small charge of powder intended for controllable recoil in small-frame automatics.The world’s most popular pistol round, the 9x19mm Luger or Parabellum (most just call it the 9mm) was designed for military and police applications and can be carried in the appendix position. Militaries and police take advantage of the cartridge’s superior ballistic characteristics and relatively lightweight.

More than half of US police are issued 9mm handguns and the FBI has switched back to it being their standard issue pistol. It also remains one of the most popular ammunition types for submachine guns as well. Its secret lies in the high velocity of the relatively small round; while only three-hundredths of an inch wider than a .32 ACP.

The 9mm rounds are light, affordable, and nearly ubiquitous, making them an excellent choice for regular practice. 9mm rounds are a common choice for self-defense, especially in hollowpoint configurations designed to expand on impact. 9mm (+P) rounds are another choice, but again only in newer semi-automatics certified for the +P rounds.

On that note….if you do not know what +P or +P+ means check out the following links. We had thought about writing about this topic, but after reviewing these we decided there was no need. to. They will help you understand this topic easily.

1. ​Overpressure Ammunition​​​
2. ​Understanding +P Ammunition​​​

.40 S&W 

• Typical Weight Range:  135-200 gr
• Typical Velocity Range: 907-1324 fps 
• Typical Muzzle Energy Range: 363-524 ft.lbf

10 mm Auto 

• Typical Bullet Weight Range:  155-200 gr
• Typical Velocity Range: 950-1340 fps 
• Typical ME Range: 361-680 ft.lbf

The forty-caliber cartridges, .40 Smith & Wesson and its longer cousin, 10mm Automatic, offer larger, heavier bullets than most pistol cartridges without sacrificing too much in the way of velocity. Initially developed in the 1980s, the 10mm Auto rose to brief prominence after the FBI selected the round to replace their .38 Specials and 9mms. This decision was made in the wake of a disastrous shootout in Miami.

During the shooting, a bank robber was able to continue killing and wounding FBI agents despite having been struck half a dozen times by their handgun bullets. The big 10mm round and large powder charge proved seriously capable in the right hands, but field testing revealed that the powerful recoil and large size of handguns chambered in 10mm made it difficult for most law enforcement officers to make follow-up shots reliably.

A shortened spinoff, the .40 S&W, garnered widespread acclaim and rapidly became one of the most popular defensive hangun calibers. In many senses, .40 S&W straddles the line between the small, high-velocity 9x19mm round and the large, lower-velocity .45 ACP; many varieties exist which allow shooters to select their favorite balance of mass and projectile velocity.

.45 ACP & .45 ACP (+P)

• Typical Weight Range:  185-230 gr
• Typical Velocity Range: 770-1140 fps 
• Typical Muzzle Energy Range: 244-534 ft.lbf.

​One of the twentieth century’s best-known pistol cartridges, the old.45 Automatic Colt Pistol cartridge originally supplanted the .38 Long Colt cartridge after the Moro uprisings in the Philippines showed a need for better stopping power in the pistol cartridges issued to the US military. (For more information on the history of this old cartridge, check out our guide to the best IWB holsters for 1911 pistols.

Its low muzzle velocity is sufficient for penetration, and the round relies on its weight for its lethal characteristics. A pistol caliber comparison chart will typically list this as the largest of common self-defense rounds by caliber alone. While it lacks the sheer destructive power of other large cartridges such as the .44 Magnum, the .45 ACP allows for much quicker follow-up shots due to its lower recoil. On the downside, the round’s large diameter means that most handguns chambered for this cartridge hold fewer rounds than their 9mm or .40 S&W equivalent.

Deciding Which Caliber is Right for You? 

Remember, we did warn you this is an in-depth topic, but you must understand it. If you know the concepts but still are looking for help to decide which caliber is right for you, we have made this decision tree to simplify the process. 

FAQ:

1. What is the most effective handgun caliber?

Due to advancements in bullet designs, arguably, the 9mm is the most effective handgun caliber today. Many will disagree, but the FBI switched back to the 9 mm, and they know a thing or two about calibers.

Conclusion

To clarify, whether you’re equipping yourself for target practice (do not forget to find a great scope), hunting or self-defense, the choice of caliber can make quite a bit of difference. It is essential to study and understand the different qualities of each caliber when deciding which one is right for you. We did our best to simplify this complicated topic so that you will be able to understand it and use the knowledge to your advantage.

Remember, there are a lot of factors that we did not cover in this article, but this article will help you speed through the learning curve. Be sure to check out our other articles about ankle holsters, or belly bands to carry your gun. Purchase a holster shirt before carrying As always, let us know if we missed something below. Until next time keep them straight.