The 22 Winchester Magnum Rimfire is a rimfire cartridge standardised by SAAMI in ANSI/SAAMI Z299.1. SAAMI sets its maximum average pressure at 24,000 psi, and measures its reference velocities in a 24.000 in standard test barrel rifled 1 turn in 16 in. This guide sets out SAAMI’s published reference velocity for each bullet weight, computes the muzzle energy each one carries, and compares the 22 Winchester Magnum Rimfire with the 17 Hornady Magnum Rimfire on the same basis.
22 WMR 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 |
|---|---|---|---|
| 28 gr | JHP-NL | 2,175 fps | 294 ft-lb |
| 30 gr | JHP | 2,200 fps | 322 ft-lb |
| 33 gr | PT | 1,950 fps | 279 ft-lb |
| 34 gr | JHP | 2,075 fps | 325 ft-lb |
| 40 gr | All | 1,875 fps | 312 ft-lb |
| 45 gr | LHP | 1,550 fps | 240 ft-lb |
| 50 gr | JHP | 1,650 fps | 302 ft-lb |
What the numbers mean for a shot
SAAMI lists 7 reference bullet weights for the 22 Winchester Magnum Rimfire, from 28 to 50 grains. The lightest, 28 grains, is listed at 2,175 fps, which computes to 294 ft-lb. The heaviest, 50 grains, is listed at 1,650 fps, which computes to 302 ft-lb. The most energetic reference load is the 34-grain at 2,075 fps: 325 ft-lb computed. The fastest is the 30-grain at 2,200 fps.
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 22 WMR ammo range lists whatever its maker publishes for that item.
Barrel, chamber and pressure
SAAMI’s standard test barrel for the 22 Winchester Magnum Rimfire is 24.000 in long and rifled 1 turn in 16 in, with a .224 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 24,000 psi. Fire 22 Winchester 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.
22 WMR vs 17 HMR: 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 | 22 Winchester Magnum Rimfire | 17 Hornady Magnum Rimfire |
|---|---|---|
| Maximum average pressure | 24,000 psi | 26,000 psi |
| Standard test barrel length | 24.000 in | 24.000 in |
| Test barrel twist rate | 1 turn in 16 in | 1 turn in 9.00 in |
| Test barrel groove diameter | .224 in | .1720 in |
| Lightest reference load | 28 gr — 2,175 fps / 294 ft-lb | 15.5 gr — 2,475 fps / 211 ft-lb |
| Heaviest reference load | 50 gr — 1,650 fps / 302 ft-lb | 20 gr — 2,350 fps / 245 ft-lb |
SAAMI standardises the 22 Winchester Magnum Rimfire at 24,000 psi and the 17 Hornady Magnum Rimfire at 26,000 psi, so the 22 Winchester Magnum Rimfire runs 2,000 psi lower. 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 16 in for the 22 Winchester Magnum Rimfire; 24.000 in, 1 turn in 9.00 in for the 17 Hornady 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: 17 HMR ammo.
22 WMR ballistics questions
What is the maximum pressure of the 22 Winchester Magnum Rimfire?
ANSI/SAAMI Z299.1 sets the maximum average pressure for the 22 Winchester Magnum Rimfire at 24,000 psi.
What twist rate and barrel length does SAAMI use for the 22 Winchester Magnum Rimfire?
SAAMI’s standard test barrel for the 22 Winchester Magnum Rimfire is 24.000 in long and rifled 1 turn in 16 in. Your own firearm may differ.
What bullet weights does SAAMI list for the 22 Winchester Magnum Rimfire?
SAAMI lists 7 reference weights, from 28 to 50 grains: 28, 30, 33, 34, 40, 45 and 50.
Is the 22 Winchester Magnum Rimfire more powerful than the 17 Hornady 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 325 ft-lb for the 22 Winchester Magnum Rimfire (34 grains) and 260 ft-lb for the 17 Hornady Magnum Rimfire.
What is the effective range of the 22 Winchester 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 22 Winchester 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 22 WMR ammunition from CCI, Federal, Winchester, Remington, Hornady and Aguila. Browse the full 22 WMR ammo range.
