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In the past, I have chided the 300 Win Mag for what it isn’t. Compared to the big .30s by Weatherby, Remington, and others, for example, it isn’t much of a magnum. Compared to the 30/06, it isn’t much more capable on game. But there’s another way of looking at it: What the 300 Win Mag isn’t—overly powerful, too hard-kicking, terribly expensive—goes a long way toward explaining what it is: one of the most popular and useful magnums cartridges around.
Origin Story of the 300 Win Mag
In 1962 Remington introduced its weak-kneed and flaccid 7mm Remington Magnum. Since only eight people in the United States who did not work for a gun company had chronographs, and since the things were such a pain in the ass to use that only four of those eight actually consulted them, the new cartridge became a raging success.
Winchester, stung by the failure of its 264 Winchester Magnum, felt obliged to do something. And they did. But rather than bring out a competitive 7mm mag, they turned to the .30 magnums.
Despite the success of the 300 Weatherby, Winchester designed a cartridge with considerably less power. Their reasoning was sound. While the Weatherby’s ballistics were spectacular, so was its recoil and the cost of the ammo. It also required a magnum-length action.
So, the new 300 Winchester Magnum was based on a short-necked case that would work through a 30/06-length action and would push a 180-grain bullet at a real-world 2,950 fps, while the Weatherby shot the same slug at 3,150. The smaller case cut down on cost while the lesser powder charge reduced the recoil and muzzle blast.
A Stellar Big-Game Cartridge
The 300 Win Mag was, and is, a solid success. For the insane, and those who are mesmerized by very high initial velocities with light bullets (often the same people), it moves 150-grain slugs at 3,200 fps and more and 165s at 3,100 plus. But it’s the 180-grain bullets, at a solid 3,000 fps or just under, that do the real heavy lifting.
The 300 Win Mag is a big-game cartridge, not a deer and antelope cartridge, and here you have enough bullet weight to do the job on hefty critters combined with a very flat trajectory. And there’s more. The 300 Win Mag will really shoot. For all its power, it’s capable of uncanny accuracy.
The first rifle Kenny Jarrett built for me was a 338. When I took delivery he said, “If you ever want a gun that’ll really shoot, I’ll build you a 300 Win Mag.” And so, in 1989, he did, and it shot 180-grain Nosler Protected Point Partition bullets into .490-inch which, at that time, was unheard-of for a straight-up hunting rifle, and is still pretty damned good.
(As an aside: The Nosler Protected Point Partition may seem an unlikely choice for a long-range cartridge because it has a low BC of .361, which is to sneer at these days. However, Kenny had observed that, for whatever reason, the Protected Point gave exceptional accuracy. I found exactly the same thing. More important, it’s effective. I can’t recall ever sending a second Protected Point after any animal.)
Roughly 20 years later, I shot another of Kenny’s 300 Win Mag sporters. This one turned in groups of .330-inch, and his rifle tuner, who had worked up the load, was getting much smaller than that, something like .220. Not all 300 Win Mags will shoot like this, but these days, there’s no shortage of rifles that will, if you’re willing to spend the money.
Read Next: The 30/06 Vs. the 300 Winchester Magnum
The 300 Win Mag as Sniper Rifle or Hunting Rifle
If there was ever the slightest doubt about the effectiveness of the 300 Win Mag, it was dispelled nine years ago when the Army picked the cartridge for its M2010 sniper rifle. And in 2018, the Marine Corps gave the round the nod for its Mk13 M7 sniper rifle, replacing the 7.62 NATO cartridge.
The 7.62 is officially effective to 1,000 yards (though, it will do the job farther out.) The 300 Win Mag officially reaches to 1,300, plus. It’s worth noting that the bullet selected for the 300 Win Mag is the 220-grain Sierra MatchKing, which begins its journey at a modest 2,850 fps, but keeps most of that velocity Way Out There.
Over the years, I’ve owned, I think, six 300 Win Mags and six 270 Winchesters, and shot pretty much the same selection of game with each. Inside 300 yards, if there’s a real-world difference between a 150-grain 270 bullet at 2,950 fps and a 180-grain 300 Win mag bullet at the same velocity, it has to be in your fevered imagination. The one difference that does exist is, of course, the .270 will kick you a hell of a lot less.
But beyond 300 yards, if you feed it low-drag 200- or 220-grain bullets, the 300 will badly outrange the 270. It remains one of the premiere long-range cartridges in the world.
Read Next: Nothing Works Better Than a 338