The .300 Winchester Magnum

The .300 Winchester Magnum was the fourth and last of Winchester’s original family of “short magnums” intended to fit into .30-06-length actions. Today, with the Winchester Short Magnums (WSMs) and Remington Short-Action Ultra Magnums (RSAUMs) short magnum has a different connotation. Fifty years ago it suggested a belted cartridge, probably based on the .375 H&H case but shortened enough to fit into a standard or .30-06-length action. The concept was hardly new; Roy Weatherby’s .257, .270, and 7mm Weatherby Magnums, all developed in the 1940s, can be so described. In fact, it was probably Weatherby’s aggressive marketing that got the majors moving.

The .458 Winchester Magnum was introduced in 1956, followed by the .264 and .338 Winchester Magnums in 1958. There was a hiatus of five years before the .300 Winchester Magnum was released in 1963. It was preceded in 1960 by the .308 Norma Magnum, which is essentially the wildcat .30-.338, based on necking down the .338 Winchester Magnum. This probably caused Winchester a bit of a dilemma in creating its own .30-caliber magnum. The first three (.458, .264, and .338) Winchester Magnums had 2.5-inch cases, as does the .308 Norma Magnum. The .300 Winchester Magnum has a case slightly lengthened to 2.620 inches, with a very short neck, thus increasing powder capacity.

Winchester’s .300 didn’t exactly take off like a rocket—in part, because of poor timing. Only a year earlier, in 1962, Remington introduced its 7mm Remington Magnum. It was already blowing Winchester’s .264 off the market, and for a time would be the world’s most popular belted magnum cartridge. Too, the .300 Winchester Mag was introduced in the final year of the pre-1964 Winchester Model 70. It was a replacement for the old, full-length (2.850-inch) .300 H&H with its archaic tapered case, which meant it had pretty big shoes to fill in the first place. Then came the shift to the post-1964 push-feed action with modern stock design. Shooters weren’t happy, and they were looking for things to pick on.

Like so many American hunters, my buddy Mike Hagen, right, uses the .300 Winchester Magnum as his go-to rifle for just about everything, including this old, heavy-antlered whitetail taken on my neighbor’s farm in southeast Kansas. 

With the .300 Winchester Magnum, the biggest complaint was the short neck. Case design theory had long held that a centerfire cartridge needed at least a “one-caliber neck” to properly grip the bullet and allow consistent propellant ignition and bullet acceleration. This means that, say, a cartridge firing a .308-inch bullet should have a case neck of at least .308-inch. The .300 Winchester Magnum has a short neck of just .264-inch. The obvious reason was to offer as much powder capacity as possible. Winchester was still smarting from the blue sky it had put into original published figures for the .264. They knew the .300 had to do exactly what they said it would do! This it did, but a disadvantage to the short neck is that, especially with heavier bullets, projectiles must be seated so that they protrude into the powder space. So, while the .300 Winchester Magnum does very well with standard .30-caliber hunting bullets from 150 to 180 grains, it starts to lose ground with extra-heavy bullets of 200 grains and more.

With the better bullets we have today, relatively few hunters use the extra-heavies. With bullets from 150 to 180 grains, the .300 Winchester Magnum provides very good performance, and does it from a 24-inch barrel. This is important, because the old .300 H&H and the upstart .300 Weatherby Magnum, both based on longer cases, really need 26-inch barrels to reach optimum performance. Original specs for the .300 Winchester Magnum were a 150-grain bullet at 3,290 feet per second (fps); and a 180-grain bullet at 2,960 fps. These velocities remain pretty standard today, but there are a lot more options in bullet weights and newer propellants have allowed a bit more velocity. Just the other day I chronographed a batch of Hornady Superformance .300 Winchester Magnum with 180-grain SST bullets, and the velocity was just shy of 3,200 fps, which is actually very deep into .300 Weatherby Magnum territory.

It took time, but the .300 Winchester Magnum eventually overcame both the stigma of the short neck and its association with the demise of the beloved pre-1964 Model 70. Accuracy is actually very good—good enough that, ever since the first Gulf War, a lot of our Special Operations snipers have gravitated to it. As a hunting cartridge, it persevered and eventually became a world standard. For a time, it was the second-most popular magnum cartridge after the 7mm Remington Magnum. Today it has surpassed the 7mm Remington Magnum: It is the world’s most popular belted magnum, the world’s most popular cartridge to bear the magnum suffix, and, among so many, the world’s most popular fast .30-caliber cartridge.

I think the first North American animal I took with the .300 Winchester Magnum was this superb Sitka blacktail, taken with my hunting partner’s Model 70 at about 375 yards. This is probably my very best deer, still listed in our All-time record book.

Personally, it isn’t my favorite. I prefer the .300 Weatherby Magnum because I’m used to it, and I can get a wee bit more velocity. Come to think of it, I probably also like the great old .300 H&H better; that preference based purely on nostalgia. But the .300 Winchester Magnum is more popular than those two—and probably more popular than all the other fast .30s put together. In my business as a gun writer, it is an almost unavoidable cartridge—whether I prefer it or not! Everybody loads for it, and the load selection is rich. Regardless of its short neck, it tends to be extremely accurate as well as popular, so over the years a lot of test guns have turned up in .300 Winchester Magnum.

Come to think of it, over the years I’ve owned several rifles chambered to .300 Winchester Magnum, so while it has never been a conscious favorite, I certainly don’t dislike it and have often relied on it. Like all the fast .30-calibers, it is an extremely versatile cartridge, excellent for elk in high alpine basins, able to reach out in plains, tundra, and mountains, and yet not so brutal that it can’t be housed in a fairly portable package.

Introduced in 1963, the .300 Winchester Magnum was essentially a modernized replacement for the old .300 H&H. It is not as fast as the .300 Weatherby Magnum, but produces very credible velocity from a .30-06-length action.​​​​​​​

Rifle nuts like me are bound and determined to split hairs and find fault where there really isn’t any—and equally likely to come up with some oddball choice just to be different, just because we can. So sometimes we aren’t the best examples to follow. Here is the truth: The .300 Winchester Magnum is a fine choice for hunters in search of just one cartridge for the full gamut of North American big game. It’s a bit light for the big bears, but heavy bullets can up the ante. It’s more powerful than necessary for a lot of deer hunting—but on deer, elk, sheep, goat, caribou, and even moose, there is no sensible shot it can’t handle. And its lasting popularity is a huge advantage: Ammo isn’t hard to find, and I doubt it ever will be!