.300 Win Mag Vs .308 Win: Battle For Best .30 Cal

BATTLE OF THE .30 CALS: WHAT CARTRIDGE IS RIGHT FOR YOU?

The .300 Winchester Magnum and the .308 Winchester are both insanely popular cartridges for both big game hunting and high-stakes target competition. Each has a dedicated fan base willing to throw arguments (and fists if necessary) to defend the virtues of their own beloved cartridge. 

This particular .30-caliber debate has been raging since at least 1963 (when the .300 Win Mag hit the market). The .300 Win Mag Vs. .308 Winchester bickering often rears up around campfires, skinning sheds, and gun ranges and has probably triggered the end of more than one friendship. 

This article probably won’t settle arguments or repair any broken relationships. However, this is more than an attempt to throw our two pennies into the scuffle. Our main goal is to break down the benefits and drawbacks of each cartridge, so you, dear reader, can make an informed decision all on your own. 

A BRIEF HISTORY LESSON

Understanding where you’re going often begins with understanding where you’ve been, so we’ll start this comparison with a brief look at cartridge history.

Introduced in 1952, the .308 Winchester is the more seasoned cartridge in this debate. It was originally developed by the US Army to replace the long-standing .30-06 Springfield. However, the .308 Win was introduced to the civilian world before it saw actual military service.

The .308 Win is based on the .300 Savage, only the newer cartridge has less taper. The goal was to design a cartridge that could produce muzzle velocities comparable to the M2 .30-06 but would function in a lighter, more maneuverable, easier to tote short-action rifle.

The .300 Winchester Magnum was released just over a decade later. It was one in a series of belted, bottleneck magnum cartridges Winchester developed based on the .375 Holland & Holland Magnum. Unlike the .375 H&H, which requires a longer action to function, the .300 Win Mag fits in a standard-length action. 

Although the .300 Win Mag was originally engineered for big game hunting rather than military use, it has been used in adapted XM24A1 Sniper Weapon Systems and fully adopted in the M2010 ESR.

BREAKING IT DOWN

Although both the .300 Win Mag and the .308 Winchester shove .30-caliber bullets, there are plenty of differences between these two cartridges – including in-flight performance and on-target energy. There’s even a substantial difference in the rifles that shoot them. 

Cartridge Size

If you stand the .300 Win Mag and .308 Winchester side by side, even an untrained eye can immediately see the difference. The .300 Win Mag stands 3.34 inches tall with a case length of 2.62 inches. That case is also fatter, which provides plenty of interior elbow room. 

The shorter, more slender .308 measures just 2.8 inches long, with 2.015 inches of that being the case.   

The .308 Win is also significantly shorter than the Golden Child of .30-caliber cartridges, the .30-06 Springfield. It’s one reason the .308 is sometimes lightheartedly, if not disrespectfully, referred to as the “30 Not Six.”

While the .308’s shorter, less-roomy case sacrifices powder capacity (and therefore speed and power), it has several other advantages. Because the .308 is a half-inch shorter than both the Win Mag and the venerable “aught six,” it fits in a shorter, lighter, faster-cycling action. 

A lighter rifle and lighter ammo are blessings in the backwoods. If you’ve ever had to hike miles through rough terrain, you understand that ounces equal pounds, and pounds equal pain. If you are a hunter that hikes further than a mile or so from the truck, you’ll be thankful to have the more portable .308 slung over your shoulder. 

Case Capacity

With its relatively spacious case, the .300 Win Mag holds 93.8 grains of powder. The more compact dimensions of the .308 case only provide enough room to hold a mere 56 grains. 

All that extra propellant gives the Win Mag several serious advantages over its smaller .30-caliber cousin. 

The first advantage is horsepower. The .300 Win Mag drives a .30-caliber 150-grain bullet a good 450 fps faster than the .308 Win. 

With plenty of extra oomph behind it, the .300 Win Mag can push longer, heavier bullets with better ballistic coefficients. That means the .300 Win Mag delivers flatter trajectories. (It has 15 fewer inches of drop at 500 yards.) It also does a much better job of bucking the wind. 

The horsepower advantages don’t end there. 

Heavier bullets traveling at faster speeds produce heftier terminal energy. A 180-grain bullet fired from a bolt-action .300 Win Mag leaves the muzzle carrying around 3500 foot-pounds of energy, and that bullet is still hauling over 1500 foot-pounds of that energy at 500 yards.

Compare that to a 150-grain spitzer shot from a .308 Winchester rifle. Right out of the gate, the .308 Win is toting 850 foot-pounds less energy than the .300 Win Mag. At 500 yards, the .308 Win is packing a paltry 890 foot-pounds, which makes attempting ethical shots on deer-sized game at that distance a risky affair. 

The Downside of Power

While the .300 Win Mag wins the horsepower category with its hands tied behind its back, all that extra power comes at a cost.

Recoil

Just like good old Isaac Newton warned us in his Third Law of Motion, “For every action, there is an equal and opposite reaction.”

In the world of shooting, that opposite reaction is recoil.

While it may be more well-mannered than most other .300 magnums, the .300 Winnie produces nearly twice the recoil energy as the .308. I’ve seen big, burly men balk at the recoil after just a few rounds.

Even if you aren’t “recoil sensitive,” you shouldn’t underestimate the impact recoil can have on your shooting performance. With some time and effort, you can train yourself out of an anticipatory flinch. However, weighty recoil will still make it harder to recover after the shot. If you need to get back on target fast and make accurate follow-up shots, a milder recoiling cartridge (like the .308 Win) will quickly become your new best friend.

Heavy recoil can also be a burden for high-volume shooters. Sending dozens of rounds of .300 Win Mag downrange in practice can wear you out in a hurry. While .300 Win Mag certainly has ballistic advantages for long-range shooters, honing your shooting skills can quickly start to feel like punishment. 

Barrel Life

Because .300 Win Mag and .308 Win both shoot .30-caliber projectiles, the rifles that shoot these cartridges also feature barrels of identical diameter. That means the powder is burning in a similarly sized space. 

However, since the .300 Win Mag burns significantly more powder, it can wreak serious havoc on your rifle’s barrel.

Exact numbers will greatly depend on what load you shoot, what kind of barrel you shoot it from, how you shoot it, and what standards you expect from it – but generally speaking, .300 Win Mag has a barrel life of about 1,000-1,200 rounds. .308 Win is more in the 10,000-15,000 round ballpark.

The average hunter probably won’t run through enough .300 Win Mag ammo in their hunting career for it to matter. 

However, if you have dreams of taking your .300 Win Mag to competitions, you should expect to replace your barrel as much as several times per year, depending on how serious you are about it.

Ammo Cost and Availability

Because .300 Win Mag and .308 Winchester are both popular among big game hunters and serious target shooters, they were among the first cartridges to sell out during the tragic 2020 ammo shortage. Thankfully, those grievous times are mostly behind us now. 

Virtually any retailer peddling ammo should have plenty of load variety for both cartridges. Match-grade factory loads and ammo optimized for big game are both generally easy to find. 

Because the .300 Win Mag uses more brass and propellant than the .308, it is usually a bit more expensive. You’ll want to keep that in mind if budget is one of the main factors you need to consider, especially if you are a high-volume shooter.

A NOTE ABOUT ACCURACY

The .308 is a common sniper cartridge with a glowing track record of military and law enforcement use. With the number of precision rifles chambered for this cartridge, its long-range accuracy is a given. 

Likewise, the .300 Win Mag has proven its accuracy by winning its fair share of 1,000-yard target competitions. 

No one should argue the inherent long-range capabilities of either of these .30-caliber rock stars, especially considering the ballistic improvements of modern ammo.

However, accuracy usually lies more in the hands of the shooter than the cartridge he or she is shooting. If you are swapping out cartridges because you think it will instantly make you a better shooter, you are living in a fantasy world. 

The best way to improve accuracy is to focus on basic marksmanship and hone those skills through thoughtful and deliberate practice.

THE BOTTOM LINE

The.308 Winchester may lag behind the .300 Win Mag in speed and power, but it packs plenty of both for most deer and elk hunters. And because the .308 Win is usually packed in lighter, short-action rifles, it is a practical option for most North American backcountry hunting.

If you want to stretch your effective range well beyond 300 yards, or if you want a rifle capable of dropping large and dangerous game on this continent and abroad, choose the .300 Win Mag.

The .300 Win Mag is also a smart choice if you know you’ll be shooting targets at extreme ranges or through rough winds, whether those targets are paper, steel, or hide-covered muscle. 

READY FOR MORE?

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