Ammo Basics: Bullet Weight

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Last Updated on March 23, 2021.
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While shopping for ammunition, you may have seen information such as grain counts printed on the box. This notation refers to the weight of the bullet.

Bullet weight has a significant influence on your ammunition’s performance. Knowing how to select the right bullet weight for your intended applications will help you get more out of your firearms.

Does Bullet Weight Matter?

You may be tempted to believe that a bullet is a bullet and that no matter what its weight is, a 40-grain bullet is just as lethal as a 400-grain projectile.

Yes, generally speaking, any bullet is potentially lethal. However, there may be critical differences between two bullet weights, even within the same caliber.

First and foremost, lighter bullets offer different performance from heavier bullets. Every caliber has its own range of typical weights, and choosing the best weight for each application will help you get the best results.


Differences Between Lighter and Heavier Bullets

It is crucial to keep in mind that the absolute weight (the bullet weight in grains printed on the box) is not useful information on its own. Whether a particular value would be considered light, average, or heavy depends on the cartridge.

For example, 147 grains is typically heavy in a 9x19mm, an average weight for .308 Winchester, and it would be a very light projectile in a .300 Winchester Magnum.

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Every caliber has a range of typical bullet weights that you should keep in mind when reading the numbers on your box of ammunition.

Bullets on the lighter end of the spectrum:

  • Pros: Lower recoil. Higher initial muzzle velocity produces a flatter trajectory.
  • Cons: Wind affects trajectory more. Lower mass results in less energy transfer into the target.

Bullets on the heavier end of the spectrum:

  • Pros: More energy transfer into the target, less affected by wind.
  • Cons: Higher recoil. Lower initial muzzle velocity means the bullet drops more quickly.

Bullet weights falling somewhere in between will offer a compromise rather than a happy medium; they will produce neither the flattest trajectories nor the highest energy transfer. While they are suitable for general-purpose use, remember that a jack-of-all-trades is also a master-of-none.


Bullet Weight Ranges For Common Calibers

Without a frame of reference, it may be challenging to know what constitutes light or heavy bullets. Knowing typical bullet weight ranges for the calibers most often seen in gun shops will help you paint a clear picture.

9x19mm Parabellum

Image from Wikipedia

The three most common grainages in 9x19mm are 115-grain, 124-grain, and 147-grain, each representing good examples of light, medium, and heavy projectiles for this cartridge, respectively.

.45 ACP

Most .45 ACP ammunition is 230-grain, which is relatively slow and heavy (standard .45 ACP 230-grain ammunition is subsonic). Other typical bullet weights are 185-grain and 200-grain. 185-grain .45 ACP ammunition is relatively light and tends to be hollow-points marketed for personal defense.

.40 S&W and 10mm Auto

Both calibers share the same range of typical bullet weights; in fact, they use the same projectiles due to the fact .40 S&W is identical to 10mm Auto in every aspect except case length (.40 S&W is shorter and develops lower velocities).

180-grain ammunition is what’s considered medium for both cartridges. Heavier 200-grain bullets are more common in 10mm Auto, as the cartridge’s higher velocity can better use the higher weight. In contrast, lighter 165-grain bullets are a frequent choice for self-defense .40 S&W ammunition.

bullet weight

.38 Special and .357 Magnum

Another situation where both cartridges are identical in all but case length, .38 Special and 357 Magnum also share the same spectrum of projectile weights.

As with .40 S&W and 10mm Auto, you will see heavier bullets more frequently in .357 Magnum and lighter bullets more often in .38 Special.

Ammunition fitted with medium 125-grain bullets is standard in both calibers. 110-grain and lower make up the lighter end of the range, whereas 158-grain and up are the heavier projectiles.

.223 Remington / 5.56x45mm NATO

Although .223 and 5.56 are not the same, they are dimensionally identical and use the same bullets.

223 remington

Today, typical medium bullets are 62-grain, usually patterned after the mil-spec M855 “green tip” projectile.

In the past, 55-grain bullets were the most common, being or mimicking the older military M193 projectiles. Although still commonly available, 55-grain bullets are now considered the standard for a light 5.56 bullet.

Heavy bullets in this caliber are most often 77-grain match-grade projectiles, suitable for competition and long-range shooting.

.308 Winchester / 7.62x51mm NATO

As with .223/5.56, the same caveat of dimensional similarity applies here.

Military-specification 7.62mm NATO ammunition is 147-grain, while typical commercial-grade .308 Winchester ammo is 150-grain. Both are medium weights for the caliber, and their performance is nearly identical.

Heavier projectiles typically start at 165 grains, with 175-grain and 180-grain bullets being among the most common.

You aren’t likely to see ammunition lighter than 150 grains. Light .308 bullets are typically only used by handloaders and the occasional box of premium hunting ammunition, typically featuring 125-grain projectiles.


What to Choose for Typical Shooting Scenarios

The role played by bullet weight depends on the application. Certain activities are more tolerant of variances in bullet weight, while others require more careful consideration.

Plinking

Plinking is the one application where bullet weight matters the least. Use whatever is the cheapest and most reliable. If you’re practicing with handguns, you can choose lighter projectiles to benefit from the lower recoil; it can help make your range session more enjoyable.

Self-Defense

As long as you choose a high-quality hollow-point, bullet weight is a secondary factor in your self-defense ammunition’s performance.

However, if you’re practicing at the range, it may be a good idea to use cheaper FMJ ammunition using the same bullet weight as your (usually more expensive) hollow points.

Keeping the bullet weight similar between your training ammunition and your self-defense ammunition also prevents you from having to re-adjust your sights or your aim, as they will have similar trajectories.

In other words, if you can hit the target accurately with your cheap .45 ACP 230-grain FMJ, you should also be on target with your high-performance .45 ACP 230-grain JHPs.

Hunting

Your hunting ammunition should be soft-points made by a reputable manufacturer in a sensible hunting cartridge, such as .308 Winchester. With that said, the right bullet weight depends on the animal you’re hunting, and if you rely on the same rifle for hunting multiple species, the right grainage makes a difference.

Matching the bullet weight with the size of your game is a good practice.

Keep the light projectiles for varmints (coyote, prairie dogs), use medium-weight bullets on medium-game (white-tailed deer, antelope, hog), and save the heavier stuff for big-game or dangerous animals (elk, moose, caribou, bear, cougar).


The Bottom Line

When shopping for ammunition, knowing the grainage you need ahead of time helps you save valuable time and money. However, as important as it may be to know all about your ammo’s specs and performance, don’t forget to practice.