Ammo Review: New .17 Winchester Super Magnum, World’s Fastest Rimfire Round

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Varmints have a new reason to quake in their burrows. Winchester has introduced the .17 Winchester Super Magnum, which is not only going to be the world’s fastest rimfire round, but also one that offers a significant performance increase over the .17 HMR (see charts below). It pushes a 20-grain bullet at 3,000 fps, which is 625 fps faster than the .17 HMR. What does that extra velocity buy you?

For starters, with a 100-yard zero, you get a much flatter trajectory. Drop at 200 yards with a 20-grain bullet is just 4.1 inches, compared to 10.7 inches with the same bullet out of the .17 HMR. Perhaps more important is the .17’s ability to resist the wind, which has always been one of the weaker qualities of the Hummer. In a 10 mph crosswind, the .17 Win. Super Mag. will move 7.3 inches at 200 yards, while the .17 HMR drifts 16.6 inches.

The velocity boost should also translate to more impressive terminal performance at longer ranges. Though the .17 HMR has proven to be a very accurate round, its knockdown power on even moderate-size prairie dogs at 100 yards is just so-so.

Meet the Parent
The .17 Win. Super Mag. comes with a workingman’s pedigree. The case is based off a .27–caliber nail-gun blank, which was modified and necked down to take the .17-caliber bullet. (These blanks, which come in three calibers–.22, .25, and .27–are a big business for Winchester, according to Greg Kosteck, the company’s marketing director.) Empty, the case measures 1.200 inches (vs. 1.064 inches for the .17 HMR). And its case walls are about 50 percent thicker than the .17 HMR’s, to handle the higher pressures the round generates (33,000 psi vs. 26,000 psi for the .17 HMR).

One of Winchester’s primary goals with the new .17 was to keep it affordable. A box of 50 should retail for about $15, which isn’t much more than the .17 HMR, and is much cheaper than even bargain-basement centerfire varmint loads. Initially, Winchester is offering the cartridge in three bullet styles: a 20-grain polymer-tipped bullet, a 20-grain hollowpoint, and a 25-grain polymer tip. The heavier 25-grain bullet will have a 2,600 fps MV with 5.6 inches of drop and 7 inches of drift with a 10 mph crosswind at 200 yards.

Savage Up First
The first gun company signed up to produce rifles for the .17 Win. Super Mag. is Savage, which hopes to have rifles shipping by mid-April. Before the year is out, Kosteck says, at least two other major rifle makers will be chambering for the .17 Win. Super Mag.