Choosing the right bullet size can be one of the most confusing aspects for newcomers to firearms. When you first start exploring handguns and rifles, the sheer variety of calibers can be overwhelming.
Exploring rifle calibers only adds to the complexity.
But don’t worry, this guide will walk you through some of the most popular handgun, rifle, and shotgun calibers available. We’ll break down the advantages and disadvantages of each, helping you understand the nuances when Comparing Bullets.
We’ll also delve into essential bullet terminology, explain different bullet tip designs like hollow points, discuss shotgun shell sizing, and dissect the components of a complete cartridge.
By the end of this article, you’ll have a solid understanding of bullet comparisons and be well on your way to becoming a bullet expert!
Understanding Bullet Size & Caliber
Let’s start with the basics. In the firearms world, “caliber” refers to the internal diameter of a gun barrel. This measurement dictates the diameter of the bullet designed to be fired from that barrel. Calibers are typically expressed in inches or millimeters. For example, 9mm pistols fire bullets that are 9 millimeters in diameter, while .223 rifles use bullets that are .223 inches in diameter.
It’s also important to distinguish between “bullet” and “cartridge.” The “bullet” is the actual metal projectile itself, while the “cartridge” is the complete unit, including the bullet, casing, gunpowder, and primer.
Here’s a look at some common 9mm bullets, varying in weight.
Rimfire vs. Centerfire Cartridges: Key Differences
The first major distinction when comparing bullets is between rimfire and centerfire cartridges. This difference lies in how the primer is positioned and ignited to fire the cartridge.
In rimfire cartridges, the primer compound is located within the rim of the cartridge case. The firing pin strikes the rim, crushing the primer and igniting the gunpowder. Centerfire cartridges, on the other hand, have the primer located in the center of the base of the cartridge. You can easily identify a centerfire cartridge by the small, circular primer in the middle of its base.
Rimfire ammunition is typically less expensive, with .22 LR (Long Rifle) being the most popular rimfire caliber.
This animation clearly illustrates the difference in firing mechanisms:
Centerfire vs Rimfire Primer
Here you can see spent casings of both rimfire and centerfire ammunition. Notice the primer strike on the rim of the rimfire casing compared to the center strike on the centerfire casing.
For a more in-depth comparison, you can explore our dedicated article on Rimfire Ammo, or learn more about firearm mechanics in How Guns Work.
Exploring Common Bullet Calibers
The world of bullet calibers uses a mix of inches and millimeters for measurements, which can initially seem confusing. Additionally, “grain” is a unit of weight used to measure bullet and gunpowder weight. A grain is a very small unit—7,000 grains equal just one pound.
Let’s examine some of the most common bullet calibers and compare their characteristics:
.22 LR
Pros:
- Affordable: .22 LR ammunition is among the cheapest available, making it ideal for practice and high-volume shooting.
- Very Low Recoil: The minimal recoil makes it perfect for beginners, youth shooters, and anyone sensitive to recoil.
- Versatile for Plinking and Small Game: Excellent for recreational shooting (“plinking”) and controlling small pests.
Cons:
- Inadequate for Self-Defense: Generally considered underpowered for reliable self-defense against human threats.
The .22 Long Rifle is the best-selling caliber in terms of sheer volume, favored for its affordability and ease of use.
With bullet weights typically ranging from 30 to 40 grains, the .22 LR offers very mild recoil in both pistols and rifles. This negligible recoil is a significant advantage for new shooters or those uncomfortable with louder, more powerful firearms. The low cost of ammunition is also excellent for practicing shooting fundamentals and sight alignment without breaking the bank.
While primarily used for target practice and pest control (rats, snakes, birds), the .22 LR’s effectiveness for self-defense is limited. While capable of causing injury, its low stopping power may require multiple shots to neutralize a threat. For a first firearm, especially a rifle like the popular Ruger 10/22, the .22LR is an excellent starting point for learning gun safety and marksmanship.
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.380 ACP
Pros:
- Adequate for Self-Defense in Compact Pistols: Offers a step up in power for self-defense compared to .22LR, especially in small, easily concealed handguns.
- Low Recoil: Still manageable recoil, making it easier to shoot accurately, particularly in smaller pistols.
- Pocket Pistol Compatibility: Popular caliber for ultra-compact “pocket pistols” designed for concealed carry.
Cons:
- Marginally Adequate for Defense: Some argue it lacks sufficient stopping power compared to larger calibers for defensive situations.
Moving up in power, the .380 ACP (Automatic Colt Pistol) provides a noticeable increase in energy compared to the .22 LR.
Often referred to as “9mm Short,” the .380 ACP has gained significant popularity with the rise of compact concealed carry pistols. For personal defense, many consider .380 ACP to be the minimum acceptable caliber.
While offering relatively low recoil and good penetration at close ranges, the .380 ACP is still considered a lower-powered defensive round. Its effectiveness beyond close distances is limited due to bullet energy and handgun size constraints. As firearms expert Massad Ayoob famously quipped, the .380 ACP is “…barely adequate, and others will say it’s barely inadequate.” It represents a compromise between concealability and stopping power.
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9mm
Pros:
- Excellent for Self-Defense: Widely regarded as a highly effective defensive caliber with a good balance of stopping power and capacity.
- Affordable and Widely Available: 9mm ammunition is readily available and relatively inexpensive compared to larger calibers.
- Versatile Bullet Options: A vast selection of bullet weights and types are available for 9mm, catering to various needs like self-defense, target shooting, and competition.
- High-Capacity Handguns: 9mm pistols often boast higher magazine capacities compared to larger calibers, providing more rounds for defense.
Cons:
- Recoil Higher than .380 ACP: Recoil is more pronounced than .380 ACP, although still manageable for most shooters.
The 9mm (9x19mm Parabellum or 9mm Luger) is arguably the most popular handgun caliber worldwide and is often considered the “Goldilocks” round – offering an excellent balance of power, capacity, and controllability.
Despite being the same bullet diameter as the .380 ACP and .38 Special, the 9mm cartridge is more powerful due to a larger powder charge and typically heavier bullet weights. Common bullet weights range from 115 to 147 grains. For self-defense, hollow point bullets are the preferred choice for maximizing stopping power.
The 9mm is the standard service cartridge for NATO militaries and the vast majority of law enforcement agencies globally, a testament to its effectiveness and versatility. Its manageable recoil allows for faster follow-up shots and greater accuracy. Compact 9mm handguns are popular for concealed carry, and most full-size 9mm pistols offer magazine capacities of 15-17 rounds or more.
Ballistics Gel Testing
The rise of Pistol Caliber Carbines (PCCs), rifles chambered in pistol calibers, has further boosted the 9mm’s popularity. PCCs offer rifle ergonomics and handling with the affordability and effectiveness of 9mm ammunition, particularly when using hollow point rounds.
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.40 S&W
Pros:
- Increased Power Over 9mm: Offers more energy and stopping power compared to the 9mm.
Cons:
- Snappier Recoil: More recoil than 9mm, making it slightly harder to control and potentially slower for follow-up shots.
- Lower Capacity Compared to 9mm: Pistols chambered in .40 S&W typically have lower magazine capacities than comparable 9mm models.
The .40 S&W (Smith & Wesson) was developed for law enforcement, specifically for the FBI, as a “compromise” cartridge offering more power than the 9mm but with less recoil than the 10mm Auto.
If the 9mm is the “Goldilocks” round, the .40 S&W is often described as its more aggressive sibling. Bullet weights for .40 S&W typically range from 155 to 180 grains. While it delivers more energy than the 9mm, the increased recoil can make it less controllable for some shooters, potentially impacting accuracy and speed in rapid-fire situations.
Interestingly, the FBI has since transitioned back to the 9mm, citing that agents generally shoot more accurately and quickly with 9mm pistols compared to .40 S&W. This shift reflects a broader trend towards prioritizing shootability and capacity over raw power in handgun calibers for law enforcement and self-defense.
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.45 ACP
Pros:
- Large, Heavy Bullet: The .45 ACP (Automatic Colt Pistol) fires a large diameter, heavy bullet, known for its significant stopping power.
- 1911 Nostalgia and Ergonomics: Closely associated with the iconic 1911 pistol, which many shooters find ergonomically excellent.
Cons:
- Lower Capacity: .45 ACP handguns, especially 1911-style pistols, typically have lower magazine capacities compared to 9mm or .40 S&W.
- Increased Recoil: Recoil is more substantial than 9mm or .40 S&W, requiring more training and experience to manage effectively.
The .45 ACP, designed by the legendary John Browning in 1904 for the 1911 pistol, is a classic American cartridge with a long and storied history.
Firing a large, 230-grain bullet, the .45 ACP is renowned for its stopping power. It was the standard issue sidearm for the US military for decades and remains popular among civilian shooters. However, the larger bullet size and lower cartridge capacity are tradeoffs compared to smaller calibers.
The recoil of a .45 ACP is significantly more pronounced than a 9mm, making it less suitable for novice shooters. While its stopping power is undeniable, the lower capacity and increased recoil are factors to consider when comparing it to other defensive calibers.
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.38 Special & .357 Magnum
Pros:
- Revolver Cartridge: Primarily used in revolvers, offering a different operating system compared to semi-automatic pistols.
- Manageable Recoil (.38 Special): The .38 Special offers moderate recoil, making it controllable in revolvers.
- Versatile Bullet Loads: Both calibers offer a wide variety of bullet weights and loadings for different purposes.
Cons:
- Low Capacity (Revolvers): Revolvers typically have lower capacities (5-8 rounds) compared to semi-automatic pistols.
The .38 Special and its more powerful counterpart, the .357 Magnum, are classic revolver cartridges.
The .38 Special, once the standard sidearm of the FBI, offers manageable recoil, although it can still be stout in lightweight, compact revolvers. While often compared to the 9mm, the .38 Special typically uses a heavier, slower bullet.
The .357 Magnum is dimensionally similar to the .38 Special but features a longer case and a significantly higher powder charge, resulting in much greater velocity and energy.
A key advantage is that you can safely fire .38 Special rounds in a revolver chambered for .357 Magnum, offering versatility in recoil and power levels. However, firing .357 Magnum rounds in a .38 Special revolver is dangerous due to the higher pressures. Bullet weights for both calibers range from approximately 110 to 158 grains.
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7.62x39mm
Pros:
- Standard AK-47 Round: The iconic cartridge of the AK-47 and SKS rifles, widely available and historically affordable.
- Effective and Powerful: Offers good stopping power and penetration, effective for hunting and general-purpose use.
Cons:
- Moderate Recoil: Recoil is more significant than .223/5.56mm, though manageable for most experienced rifle shooters.
The 7.62x39mm is a Soviet-designed cartridge, synonymous with the AK-47 rifle.
Typically firing a 123-grain bullet, the 7.62x39mm provides a good balance of power and controllability. Surplus military ammunition has historically been readily available, making it a relatively affordable option for high-volume shooting.
Compared to the 5.56x45mm, the 7.62x39mm bullet is larger in diameter and heavier, generally delivering more energy on target, although with a more curved trajectory at longer ranges.
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.223 / 5.56x45mm
Pros:
- Standard AR-15 Round: The most common caliber for AR-15 rifles and similar platforms, with a vast selection of rifles and accessories available.
- Fast, Flat-Shooting, and Lighter Recoil: Offers a flatter trajectory and less recoil than 7.62x39mm, facilitating faster follow-up shots and increased accuracy, especially for new shooters.
Cons:
- Debated Effectiveness: The terminal effectiveness of the 5.56x45mm in combat and self-defense situations is a subject of ongoing debate, with some arguing for larger calibers.
The .223 Remington and 5.56x45mm NATO are very similar cartridges and are the dominant calibers for modern sporting rifles like the AR-15.
While dimensionally almost identical, the 5.56x45mm NATO operates at higher pressures than the .223 Remington. Therefore, while .223 rounds can generally be safely fired in rifles chambered for 5.56mm, firing 5.56mm rounds in rifles chambered only for .223 Remington may be unsafe due to overpressure.
Typically using bullets around 55 grains in weight, the 5.56x45mm is characterized by its high velocity and relatively flat trajectory. The light recoil makes it easy to shoot accurately and rapidly, especially in semi-automatic rifles.
As the standard ammunition for the M16/M4/AR-15 family of rifles, the 5.56x45mm is one of the most widely used rifle cartridges globally. Its effectiveness in combat and for self-defense remains a topic of debate, with discussions often focusing on bullet design and fragmentation characteristics.
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.308 / 7.62x51mm
Pros:
- Powerful and Versatile: Offers significantly more power than .223/5.56mm, suitable for hunting larger game and long-range shooting.
- Effective at Longer Ranges: Retains energy better at longer distances compared to smaller calibers.
Cons:
- Heavier Recoil: Recoil is more substantial than .223/5.56mm, requiring more robust rifles and potentially affecting shooter fatigue in high-volume shooting.
- More Expensive Ammunition: .308/7.62x51mm ammunition is generally more expensive than .223/5.56mm or 7.62x39mm.
The .308 Winchester and 7.62x51mm NATO are also very similar cartridges, with the 7.62x51mm being the military designation and the .308 Winchester being the commercial version.
Like the .223 and 5.56, there are slight differences in specifications, with 7.62x51mm sometimes having slightly thicker case walls. It’s generally recommended to use the cartridge specifically designated for your rifle unless you have expert knowledge of reloading and cartridge compatibility.
The .308/7.62x51mm is a popular hunting cartridge, offering significant stopping power for medium to large game. Bullet weights typically range from 150 to 208 grains. It is also a widely used military sniper and machine gun cartridge, valued for its power and effective range.
Alt text: A variety of 7.62x51mm rounds including MEN 147gr, PPU 165gr, PPU 180gr, and Gold Medal 168gr, demonstrating the range of bullet weights and manufacturers.
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.50 BMG
Pros:
- Extremely Powerful: The .50 BMG (Browning Machine Gun) is one of the most powerful commercially available rifle cartridges, capable of extreme long-range accuracy and immense energy on target.
- Iconic and Impressive: Its sheer size and power make it an object of fascination for many firearm enthusiasts.
Cons:
- Harsh Recoil: Recoil is very significant, requiring specialized rifles and experienced shooters.
- Expensive Ammunition and Rifles: .50 BMG ammunition and rifles are very expensive and not practical for general use.
The .50 BMG is in a class of its own. While not commonly used by civilians for typical shooting activities, it’s included here to illustrate the extreme end of the caliber spectrum.
Firing a massive 660-grain bullet, the .50 BMG generates enormous recoil and is capable of accurate shots at distances exceeding 2,000 meters (over 1.2 miles). Its primary applications are military and extreme long-range target shooting.
Firing a .50 BMG is an experience unlike any other, but its impracticality and expense limit its appeal to most shooters.
Still with me? Let’s move on to bullet types and terminology.
Common Bullet Types & Terminology
Beyond caliber, the type of bullet also significantly impacts performance. Let’s compare some common bullet types:
Full Metal Jacket (FMJ)
Full Metal Jacket (FMJ) bullets are the most common type, consisting of a soft lead core encased in a harder metal jacket, typically copper.
FMJ bullets are characterized by their pointed, round-nose, or flat-nose shapes. They are designed to penetrate targets easily, creating relatively small wound channels and often passing completely through the target. FMJs are ideal for target practice due to their lower cost and reliable feeding in firearms, but they are generally not preferred for self-defense as they are less likely to expand and transfer energy effectively to the target.
Hollow Point (HP)
Hollow Point (HP) bullets are designed to expand upon impact. They feature a cavity or “hollow point” at the tip, which, upon hitting a soft target, causes the bullet to mushroom or expand, creating a larger wound channel and transferring more energy to the target.
Hollow points are the preferred bullet type for law enforcement, concealed carry holders, and home defense due to their enhanced stopping power and reduced risk of overpenetration, which can minimize collateral damage.
Open Tip Match (OTM)
Open Tip Match (OTM) bullets resemble hollow points due to the opening at the tip. However, this opening is primarily a result of the manufacturing process and not intended for significant expansion.
FMJ bullets are typically manufactured starting with a copper cup, with the bottom of the cup forming the bullet’s tip. OTM bullets are made in reverse, with the base of the copper cup becoming the base of the bullet, resulting in the open tip at what appears to be the “front.”
OTM bullets, sometimes referred to as Open Tip Match, are favored by long-range and precision shooters. The manufacturing process for OTM bullets often results in greater consistency and concentricity compared to FMJ bullets, contributing to improved accuracy, especially at extended ranges.
Ballistic Tip
Ballistic Tip bullets aim to combine the aerodynamic advantages of FMJ bullets with the expansion characteristics of hollow points. These bullets feature a hollow point cavity covered with a polymer tip, often brightly colored (e.g., red).
Alt text: Assortment of 6.5 Creedmoor rounds including FMJ, Soft Point, Ballistic Tip, and Gold Medal Match, highlighting the red polymer tip of the Ballistic Tip bullet.
The polymer tip enhances the bullet’s ballistic coefficient, improving its flight characteristics and reducing drag. Upon impact, the tip is driven into the hollow point cavity, initiating rapid expansion. Ballistic tip bullets are primarily used for hunting and precision shooting, offering a balance of accuracy and terminal performance.
The streamlined base of the bullet, known as a “boat tail” design, further reduces drag during flight, improving long-range accuracy. Hollow Point Boat Tail (HPBT) bullets combine these features for enhanced performance.
Soft Point
Soft Point bullets represent an earlier attempt to achieve bullet expansion while maintaining some of the aerodynamic benefits of FMJ designs.
Alt text: Assortment of 7.62x39mm rounds including FMJ, Open Tip, Soft Point, and another FMJ, demonstrating the exposed lead tip of the Soft Point bullet.
Soft point bullets feature a portion of the soft lead core exposed at the tip. Upon impact, the exposed lead is designed to flatten and expand, increasing the bullet’s wound channel. However, ballistic tip bullets generally offer superior and more consistent expansion performance compared to soft point designs.
Shotgun Shells: A Different Approach
Shotguns utilize a different ammunition system compared to handguns and rifles. The most common shotgun gauge is 12 gauge.
Recoil in shotguns can range from moderate to significant depending on the load. Shotgun ammunition is incredibly versatile, with three primary load types:
Alt text: Opened 12 gauge shotgun shells: birdshot, buckshot, and slug, revealing the internal components and projectile types of each load.
Birdshot
Birdshot shells are filled with numerous small lead or steel pellets.
Alt text: Opened 12 gauge birdshot shell, showing the numerous small pellets inside, designed to spread upon firing.
Primarily used for hunting birds and clay target shooting, birdshot is not ideal for home defense due to its limited stopping power against human threats at typical self-defense distances. Recoil is relatively mild compared to other shotgun loads.
Buckshot
Buckshot is considered the best all-around shotgun load for home defense. 00 Buck (“double-aught buck”) is a standard and highly effective load.
Alt text: Opened 12 gauge 00 buckshot shell, displaying the nine large lead balls inside, each comparable in size to a 9mm bullet.
00 Buckshot shells contain multiple large lead balls (typically nine in 12 gauge), each roughly the diameter of a 9mm handgun bullet. Upon firing, these balls spread out, increasing the chance of hitting a target and delivering significant stopping power. Recoil is considerably higher than birdshot, although reduced-recoil buckshot loads are available.
Slugs
Slugs are single, large projectiles made of solid lead, offering maximum energy transfer to a target.
Alt text: Opened 12 gauge slug shell, revealing the large, single lead projectile, designed for maximum impact and penetration.
While slugs lack the spread of birdshot or buckshot, they offer greater accuracy at longer ranges and deliver tremendous force. In the hands of a skilled shooter, slugs can be accurate out to 100 yards or more.
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Components of Common Cartridges
Let’s briefly examine the components that make up a cartridge. Here are breakdowns of three popular calibers:
As you can see, the basic components are consistent across different calibers, but the size and proportions vary significantly, influencing the performance characteristics of each cartridge.
Final Thoughts
Congratulations, you’ve now explored a wide range of bullet calibers and types! You’re well on your way to becoming a bullet pro.
To continue your learning, delve deeper into Popular Handgun Calibers, Popular Rifle Calibers, or understand the differences between Steel Cased and Brass Ammo. You can also explore where to Buy Ammo Online when you’re ready to stock up.
And for expert guidance for beginners, consider checking out Gun Noob to Gun Slinger, an expertly designed handgun course.
LATEST UPDATES
June 21, 2024 – Pros and cons added to caliber descriptions and minor content revisions throughout.
