Last reviewed: 2026-04-19 by Jake Terry, FFL07/SOT3, NRA-certified firearms instructor.
The 17 HMR ammo platform redefined rimfire hunting when it launched, and Winchester’s Super X load exemplifies why. This 50-round box chambers a 20-grain Hornady XTP jacketed hollow point — a bullet engineered for controlled expansion across a wide velocity window. At 2375 fps from the muzzle, this supersonic load flattens trajectory compared to traditional .22 Magnum, giving you a cleaner hold on varmints from 50 to 150 yards. For hunters working pastures, fence lines, or crop edges where precise shot placement matters, the 17 Hornady Magnum Rimfire delivers both speed and expansion in a platform-legal package. Winchester manufactures this ammunition in the United States using rimfire-primed brass cases and precision-metered powder charges.
Load Profile
The Hornady XTP hollow point is the defining feature here. XTP stands for eXtreme Terminal Performance — a six-petal cavity design that initiates expansion on contact with soft tissue, then maintains weight retention through a thick jacket wall. In gelatin testing, 20-grain XTP bullets routinely expand to 0.26–0.28 inches (1.5x their 0.172-inch bore diameter) while retaining 90+ percent of core weight. Muzzle energy of 250 ft-lbs exceeds .22 WMR by roughly 30 percent, translating to cleaner anchoring on coyote-sized game when shot angles are ideal. The supersonic velocity rating means the bullet remains above 1100 fps well past 100 yards, minimizing wind drift and hold-over compared to subsonic rimfire options.
Specs at a Glance
| Spec | Value |
|---|---|
| Caliber | 17 Hornady Magnum Rimfire (HMR) |
| Bullet weight | 20 grains |
| Bullet type | Jacketed Hollow Point (Hornady XTP) |
| Muzzle velocity | 2375 fps |
| Muzzle energy | 250 ft-lbs |
| Rounds per box | 50 |
| Case | Brass, rimfire-primed |
| Lead free | No |
| Corrosive | No |
| Intended use | Hunting (varmint/predator) |
| Velocity rating | Supersonic |
| Country of origin | United States |
| Manufacturer | Winchester |
This load suits bolt-action and semi-auto rifles chambered in 17 HMR — verify your rifle’s chamber specs before ordering. For more varmint-optimized rimfire options, browse our full 17 HMR ammo inventory.
Safe Handling & Compliance
Federal law requires purchasers to be at least 18 years old for rifle and shotgun ammunition, and at least 21 for handgun ammunition. Ammunition cannot be shipped to certain states, counties, and cities — review our ammunition shipping restrictions before ordering. Store ammunition in a cool, dry location away from heat sources and out of reach of unauthorized users.
- Observe the four universal rules of firearm safety at all times — treat every firearm as loaded, keep your finger off the trigger until ready to fire, never point the muzzle at anything you are not willing to destroy, and know your target and what lies beyond it.
- Verify that your state and local jurisdiction permit possession and use of this ammunition — some states impose magazine capacity limits, bullet-type restrictions, or require permits for ammunition purchases.
- This ammunition contains lead, a substance known to the State of California to cause cancer and reproductive harm (Prop 65). Wash hands thoroughly after handling and avoid indoor use without adequate ventilation.
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