Why You Need A .17 Win. Super Mag.

In terms of topnotch rimfire performance, the new .17 Win. Super Mag. delivers in spades.

The term “varmints” seems quaint, with the majority of us living in cities and the rest of us pretty removed from producing our own food and fiber. How long has it been since you’ve had a fox in your hen house or a coon in your corn?

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Well, if you’re like an increasing number of us who are planting gardens and starting backyard egg production, probably rather recently! And if you own a lawn or outbuilding, you’ve probably had run-ins with gnawing, burrowing rodents. So varmints it is! And varmint rifles to the rescue.

Through the years rural folks have used everything from shovels and poison to WWI surplus .30-06 Springfields and single-barrel .410 “hardware store” shotguns to protect against various marauders, but the most practical and economical firearms have been, and still are, small-caliber rimfire rifles.

Rimfire cartridges are low-power, low-velocity, low-pressure, low-report and low-priced—perfect for use on varmints in settled areas. At roughly 6-10 cents per shot, the .22 LR stands as our most cost-effective round. But there are better ones, including a record-speed-setting brand-new one, that yield markedly better ballistic and terminal performance—in fact, performance pushing rimfires into competition with some centerfires.

Rimfires were born around 1835 when a Frenchman, Louis Flobert, stuck a birdshot pellet atop a musket priming cap. His BB cap was chambered in smoothbore pistols and small parlor rifles used for target shooting. This was the first self-contained cartridge ever made. When Daniel Wesson and Horace Smith saw this BB cap, they used it as a springboard to create the .22 Short in 1857. This led to a series of .22 rimfires of which the Short, Long and Long Rifle remain.

There were many other rimfires in calibers as large as .58, but all fell to the more powerful centerfires because of the inherent pressure limitations of the rimfire design. Rimfires are so-named because they depend on their thin rims being crushed to ignite the pressure-sensitive priming powder within them. High pressures can blow holes in the brass at this weak point. But for small game at close ranges, high pressures and accompanying high velocities aren’t needed, so the small caliber .22 rimfires hung on. Better than that, they flourished. Well over 3 billion .22 rimfire rounds are still fired every year.

While low cost and convenience attract shooters to .22 rimfires, the cartridge’s relatively low velocities constantly beg for augmentation. Any kid who’s ever missed low on a distant squirrel or bunny has wanted to make his .22 go faster. Winchester did that in 1959 with the .22 Win. Mag. rimfire. This elongated case pushes roughly the same 40-grain bullet as the .22 LR, but at 1,900 fps instead of 1,200 fps. This velocity is increased to as much as 2,200 fps by using lighter bullets, but long-range performance is sacrificed to the lower ballistic coefficients of such marlight projectiles. Similarly, lighter and faster bullets atop hyper-velocity Long Rifle rounds, such as CCI Stingers, sacrifice downrange energy. There’s no free lunch here.

In 2002 the .17 Hornady Mag. Rimfire (HMR) lit a fire under rimfire shooters. Here was the .22 Win. Mag. necked down to just .17-inches diameter, with a pointy, 17-grain V-Max bullet at the fore. Despite generating no more than 26,000 psi of pressure (the .22-250 Rem. hits 65,000 psi) the .17 HMR manages to push that little poison pill to 2,550 fps and deliver a deadly punch out to 150 yards. Trajectory is wonderfully flat. Sight-in 1-inch high at 100 yards and the little bullet won’t rise above nor fall below an inch from point-of-aim until 150 yards. Energy is down to just 100 fpe at 150 yards, but the effect on 2-pound ground squirrels is still quite deadly.

But the new .17 Winchester Super Magnum is even flatter. Just released this spring, it’s only the second rimfire in more than 100 years (5mm Rem. was the other) that’s built on a case larger in diameter than the .22 LR. Specifically, a .27-caliber case used in the construction industry was the basis for the .17 Win. Super Mag. (they don’t want us abbreviating it as WSM for fear someone will confuse this with the Winchester Short Magnum centerfires). This round was engineered from the start to withstand more chamber pressure (33,000 psi) than the current crop of .22 rimfires or even the .17 HMR (26,000 psi.). Winchester’s 17 is filled with 8.5 or 9.5 grains of a fine ball powder to propel a 25-grain and 20-grain bullet, respectively. The upshot is the .17 Win. Super Mag. sets a new all-time velocity record for a rimfire: 2,600 fps with the 25-grain bullet, and an impressive 3,000 fps with the 20-grain version.

This is no incremental increase, but a full 450 fps jump over the former speed champ, the .17 HMR. Using the 20-grain projectile, the .17 Win. Super Mag. shoots twice as flat as the .17 HMR and almost four times flatter than the .22 Win. Mag. It drifts half as much in the wind as the .17 HMR and three-and-a-half times less than the .22 Win. Mag. Last but not least, it carries twice as much energy as either of its nearest competitors.

Study the ballistic chart (p. 50) and you’ll see that the .17 Win. Super Mag. outperforms even the centerfire .22 Hornet in all but retained energy, and at 200 yards it even pulls ahead in that. To beat the .17 Win. Super Mag. you need to step up to the centerfire .17 Hornet, which adds 850 fps in velocity to the same 20-grain V-Max bullet. But each .17 Hornet centerfire cartridge will cost roughly $1, while each .17 Win. Super Mag. rimfire will sell for closer to 30 cents. You can shoot three times more for the same outlay.

What all this suggests is varminters now have more options than ever in easy-shooting, relatively inexpensive rimfire ammunition. Choose the .22 LR for the least expensive shooting out to 75 yards; step up to the .22 Win. Mag. or .17 HMR for up to 150 yards, and the .17 Win. Super Mag. for honest 200-yard performance, perhaps stretching out to 250 yards.

At this point it appears either Browning or Savage will be the first to marlight ket with rifles chambered for the new .17 Win. Super Mag. I’ve shot a prototype Browning M1885 single-shot in .17 Win. Super Mag. Because of its short action, it can carry a 24-inch barrel without being any longer overall than a bolt action with a 22-inch barrel. Whether the extra 2 inches will increase or decrease velocity remains to be tested.

During the 2013 SHOT Show, Savage showed off its all-new black, synthetic-stocked, B.Mag bolt action with some unusual features for a rimfire rifle. The barrel is threaded to the receiver, not press fit; rear lugs on the bolt lock the action, not the bolt handle stem; the bolt cocks on closing for easy opening; the eight-round magazine is rotary and center feeding; an Accu-Trigger sets it off. Savage was projecting the first B.Mags hitting stores by early April. By the time you read this, they might already be flying off dealer shelves and tearing up hay fields.

No other manufacturers announced rifles in .17 Win. Super Mag. at the SHOT Show, but it wouldn’t surprise me if Ruger showed up with a M77/17 bolt action chambered for the new rimfire cartridge. It appears they’d have to modify or lengthen the action and magazines to handle the longer cartridge. T/C and H&R should be able to chamber their break-action single-shots for the .17 Win. Super Mag. rather easily, too. Let’s hope they do.

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