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What Is Magnum Ammo?


Ammunition can be confusing. It even confounds the experts on occasion. Take the term “magnum ammo,” for instance. Nothing clearly defines the parameters of a magnum cartridge, and no one, including the NSSF, regulates the term.

The word “magnum” didn’t apply to ammunition initially. It’s an old Latin word that means “large, great, or important.” That ancient definition is still applicable in describing modern magnum ammunition. Simply put, magnum ammo contains extra propellant compared to a standard cartridge of similar size.

As a result, magnum ammo will provide higher gas pressure, high-velocity projectiles, more kinetic energy and will be more powerful when compared to other cartridges of the same diameter. But a slight controversy arises in determining how much more powerful a round of ammunition must be to have the term “magnum” associated with it.

For now, suffice it to say that magnum ammo will approach its target with more gusto and have more destructive intent than its standard caliber version. Bear in mind, this is a description of what the ammo does, without any rules set in stone to define the term.

What Is Magnum Ammo?

a macro photo comparing magnum ammo

From left to right: .44 magnum, .357 magnum, and 10mm magnum handgun ammunition respectively.

It’s often difficult to separate fact from fiction, and the Hollywood film industry doesn’t make it any easier. For instance, in the Dirty Harry series of movies, Clint Eastwood plays the title character, a no-nonsense police detective who carries a Smith and Wesson Model 29, a six-shot, double-action revolver chambered for the .44 Magnum cartridge.

Harry probably did more to create magnum mythology than any other character on the big screen or television. By warning a bad guy that his weapon is “the most powerful handgun in the world“ that could “blow your head clean off,” Harry gave the Model 29 and its .44 magnum ammo some impressive capabilities. 

While the Dirty Harry films did wonders for gun retailers (they could hardly keep the Model 29 in stock), most gun enthusiasts disagree that any magnum ammo, including the .44, is powerful enough to remove a bad guy’s head. But Clint Eastwood’s character is tasked with entertaining moviegoers—not educating them with accurate facts.

Magnum Ammo: Fact VS Fiction

While we are exploding myths, here are a few other tall tales and exaggerations about magnum ammunition that needs to be corrected:

Which Ammo Is Considered “Magnum?”

a photo of winchester 22 mag ammo

Magnum rimfire? Yep, that’s a thing. The .22 Winchester Magnum is an excellent varmint control cartridge.

A generic definition of magnum ammunition is typically “a cartridge equipped with a larger charge than other cartridges of the same size.” While this is essentially correct, it’s still a long way from the complete story.

So how do ammo manufacturers create a magnum cartridge? They make room for more propellants to increase muzzle velocity. With rifles, that can be accomplished by making the case wider, longer, or increasing its shoulder angles—or perhaps a combination of all three.

With handgun cartridges, it’s merely a matter of lengthening the case. You can find an example of this in the .357 Magnum cartridge, which is made by extending the .38 Special case. Smith & Wesson stretched out the case from its original 1.155 inches to 1.29 inches (a little over 1/8”). They both fire the same .357-inch bullet, but the extra powder in the magnum version gives it substantially more power.

The same holds for “Dirty” Harry Callahan’s .44 Magnum. The .44 Magnum is simply a stretched-out and more powerful version of the .44 Special case with a regular .44 caliber bullet in each. 

Popular Types Of Magnum Ammo

A photo of hornady 300 win mag ammunition

The .300 Winchester Magnum is a popular choice for hunting medium to large size game.

Now that we’ve discussed the basics of magnum ammunition, let’s take a look at some of the more popular cartridges in the chart below. Magnum ammo comes in a variety of different usage types, including handgun, rifle, and rimfire. There’s also a variety of bullet types available for magnum ammo, ranging from FMJ, JHP, LRN, and more to give shooters more options.

Magnum Handgun Ammo Popular Magnum Rifle Ammo Magnum Rimfire Ammo
.327 Magnum 7mm Remington Magnum .17 Hornady Magnum
.357 Magnum .270 Weatherby Magnum .22 Winchester Magnum
.44 Magnum .375 H&H Magnum
.454 Casull .300 Winchester Magnum
.500 S&W Magnum .338 Lapua Magnum

Magnum Shotgun Ammo?

What about shotgun ammo? There are magnum shotgun loads, however, the term “magnum” is used more for marketing than for performance. Shotgun shells are measured by length, a magnum shotgun shell isn’t any longer than a standard one. A “magnum” shell describes the number of gunpowder drams a shell of a specific length is loaded with. Generally, any shotgun shell loaded with greater than 3 drams of powder is considered to be a magnum. 

How Much Of A Difference Does Magnum Ammo Make?

The point of a magnum cartridge is to increase velocity and power.  To accomplish this you must increase the size of the cartridge casing to allow room for more gun powder. Having a larger casing, with a larger capacity, allows for higher cartridge pressures and greater velocity. To state the obvious:

Bullet Type Bullet Weight Velocity Energy
.44 Special JHP 200gr 975 423
.44 Magnum JHP 240gr 1,475 1,160
.38 Special JHP 125gr 900 225
.357 Magnum JHP 125gr 1,450 583
.41 Long Colt LFN 200gr 650 188
.41 Magnum JHP 210gr 1,560 1,135
.32 Long Colt LRN 80gr 840 126
.32 H&R Magnum JHP 85gr 1,263 301

Increasing the speed in magnums also results in a flatter trajectory and a greater impact force (terminal energy). Magnum cartridges also offer consistent long-range accuracy, delivering the extra striking power needed for deeper penetration and bullet expansion.

While the advantages of magnums over regular rounds are real, some of the improvements are relatively small. Below is a prime example.

30-06 Springfield VS 300 Winchester Magnum

The .30-06 and .300 Win Mag are two of the most popular big-game cartridges. The .30-06 has been the .30-caliber benchmark in standard ammo, and the .300 Win Mag is likely the most common .30 caliber magnum cartridge. So, how do they compare?

The .30-06 ammo averages 2,700 feet per second, pushing a 180-grain bullet from the muzzle. The Win Mag produces velocities of around 2,950 fps, or 250 fps more than the aught-six. But what does that extra case capacity give the shooter in a practical application?

The increased speed reduces bullet drop at 300 yards by about 1.3 inches. In other words, the .30-06 bullet drops about 8 inches, while the .300 Win Mag drops 6.7 inches. However, at 400 yards, the .30-06 drops a full 4 ½ inches more than the .300 Win Mag, perhaps making the Magnum a better choice for big game at longer distances.

Is Magnum Ammo Worth Shooting? 

a photo of a man shooting a revolver

If you’re planning on using magnum ammo for self-defense, be sure to get plenty of practice at the gun range.

Is magnum ammo worth it? If you’re shooting at shorter distances and don’t want to endure the fierce recoil, you might want to stick with standard ammo. Be aware that magnum ammo does have more of a kick to it than a standard cartridge. If you plan on carrying magnum ammo for self-defense, you’re going to want to put in enough range time to overcome the additional recoil and place accurate follow-up shots on target. 

What about magnum ammo for hunting? If you hunt at longer distances, magnum ammo could be well worth it. The added velocity and knock-down power could attribute to greater target accuracy and more meat on the table. Keep in mind, you’ll see the most difference in performance when using a longer barrel with a heavier bullet weight. There’s plenty of data on why the US army prefers to use 220gr .300 Winchester Magnum ammo in its long-barrel sniper rifles. 

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