The 17 Hornady Magnum Rimfire is a rimfire cartridge standardised by SAAMI in ANSI/SAAMI Z299.1. SAAMI sets its maximum average pressure at 26,000 psi, and measures its reference velocities in a 24.000 in standard test barrel rifled 1 turn in 9.00 in. This guide sets out SAAMI’s published reference velocity for each bullet weight, computes the muzzle energy each one carries, and compares the 17 Hornady Magnum Rimfire with the 22 Winchester Magnum Rimfire on the same basis.
17 HMR ballistics chart: SAAMI reference data
SAAMI lists rimfire reference loads by bullet weight and by bullet type, and publishes a nominal mean instrumental velocity for each, measured at 15 feet from the standard test barrel. Bullet types are shown as the code SAAMI prints. It does not publish energy, so the ft-lb column is computed.
Scroll the table sideways for the remaining columns.
| Bullet weight | Bullet type (SAAMI code) | Reference velocity | Computed muzzle energy |
|---|---|---|---|
| 15.5 gr | PT-NL | 2,475 fps | 211 ft-lb |
| 17 gr | PT | 2,525 fps | 241 ft-lb |
| 17 gr | PT | 2,625 fps | 260 ft-lb |
| 20 gr | JHP | 2,350 fps | 245 ft-lb |
What the numbers mean for a shot
SAAMI lists 3 reference bullet weights for the 17 Hornady Magnum Rimfire, from 15.5 to 20 grains. The lightest, 15.5 grains, is listed at 2,475 fps, which computes to 211 ft-lb. The heaviest, 20 grains, is listed at 2,350 fps, which computes to 245 ft-lb. The most energetic reference load is the 17-grain at 2,625 fps: 260 ft-lb computed.
SAAMI lists more than one reference velocity for 17 grains. Its own note says this is because a weight can carry several introductions meeting different market needs, such as reduced-recoil loads, or because propellant and loading advances allowed higher velocities after the original load appeared.
None of this is a downrange figure. SAAMI measures at 15 feet, so retained velocity, energy and drop depend on the bullet’s ballistic coefficient, which SAAMI does not publish. Each product in our 17 HMR ammo range lists whatever its maker publishes for that item.
Barrel, chamber and pressure
SAAMI’s standard test barrel for the 17 Hornady Magnum Rimfire is 24.000 in long and rifled 1 turn in 9.00 in, with a .1720 in groove diameter. That is the barrel every reference velocity above was measured in, not a statement about your firearm: rimfire barrels vary widely in length, and a shorter barrel gives lower velocity. The maximum average pressure is 26,000 psi. Fire 17 Hornady Magnum Rimfire ammunition only in a firearm chambered for it. Several unrelated cartridges share a number, so match the full designation on the box to the marking on your barrel.
17 HMR vs 22 WMR: the SAAMI comparison
A figure from one maker’s catalogue cannot be laid beside a figure from another’s: each picks its own test barrel, zero and bullet, and many publish no test barrel at all. SAAMI is the shared basis, because it fixes one standard test barrel and one way of measuring velocity for every cartridge it lists.
Scroll the table sideways for the remaining columns.
| SAAMI specification | 17 Hornady Magnum Rimfire | 22 Winchester Magnum Rimfire |
|---|---|---|
| Maximum average pressure | 26,000 psi | 24,000 psi |
| Standard test barrel length | 24.000 in | 24.000 in |
| Test barrel twist rate | 1 turn in 9.00 in | 1 turn in 16 in |
| Test barrel groove diameter | .1720 in | .224 in |
| Lightest reference load | 15.5 gr — 2,475 fps / 211 ft-lb | 28 gr — 2,175 fps / 294 ft-lb |
| Heaviest reference load | 20 gr — 2,350 fps / 245 ft-lb | 50 gr — 1,650 fps / 302 ft-lb |
SAAMI standardises the 17 Hornady Magnum Rimfire at 26,000 psi and the 22 Winchester Magnum Rimfire at 24,000 psi, so the 17 Hornady Magnum Rimfire runs 2,000 psi higher. SAAMI lists no bullet weight in common for the two, so there is no like-for-like velocity row to compare. Their standard test barrels differ (24.000 in, 1 turn in 9.00 in for the 17 Hornady Magnum Rimfire; 24.000 in, 1 turn in 16 in for the 22 Winchester Magnum Rimfire), so compare the reference rows with that in mind.
What SAAMI cannot settle is anything past the muzzle. It publishes no ballistic coefficients and no downrange data, so it cannot say which cartridge shoots flatter at distance; that depends on the bullet. We stock the other side of this comparison too: 22 WMR ammo.
17 HMR ballistics questions
What is the maximum pressure of the 17 Hornady Magnum Rimfire?
ANSI/SAAMI Z299.1 sets the maximum average pressure for the 17 Hornady Magnum Rimfire at 26,000 psi.
What twist rate and barrel length does SAAMI use for the 17 Hornady Magnum Rimfire?
SAAMI’s standard test barrel for the 17 Hornady Magnum Rimfire is 24.000 in long and rifled 1 turn in 9.00 in. Your own firearm may differ.
What bullet weights does SAAMI list for the 17 Hornady Magnum Rimfire?
SAAMI lists 3 reference weights, from 15.5 to 20 grains: 15.5, 17 and 20.
Is the 17 Hornady Magnum Rimfire more powerful than the 22 Winchester Magnum Rimfire?
SAAMI lists no bullet weight in common for the two, so there is no like-for-like row. Its highest computed reference energy is 260 ft-lb for the 17 Hornady Magnum Rimfire (17 grains) and 325 ft-lb for the 22 Winchester Magnum Rimfire.
What is the effective range of the 17 Hornady Magnum Rimfire?
Effective range is not a SAAMI specification and it is not a measured figure. SAAMI measures velocity at 15 feet, so it says nothing about performance at distance; that depends on the bullet and the shooter.
How much does the 17 Hornady Magnum Rimfire drop at 100 yards?
SAAMI publishes muzzle velocity only, so it cannot give a drop figure. Drop depends on the bullet’s ballistic coefficient and on the zero range. A drop figure is unusable without its zero, so use the figure a maker prints for the specific load.
Where to buy these loads
Hilltop Armory carries 17 HMR ammunition from CCI, Hornady, Federal, Winchester, Remington and Browning Ammunition. Browse the full 17 HMR ammo range.
