The 21 Sharp 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 12.00 in. This guide sets out SAAMI’s published reference velocity for each bullet weight, computes the muzzle energy each one carries, and compares the 21 Sharp with the 22 Hornet on the same basis.
21 Sharp 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 |
|---|---|---|---|
| 25 gr | NL | 1,725 fps | 165 ft-lb |
What the numbers mean for a shot
SAAMI lists a single reference bullet weight for the 21 Sharp: 25 grains, listed at 1,725 fps, which computes to 165 ft-lb. SAAMI publishes no other weight for it, so the table has one row. For any other bullet weight, use the figures the maker publishes for that item.
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 21 Sharp ammo range lists whatever its maker publishes for that item.
Barrel, chamber and pressure
SAAMI’s standard test barrel for the 21 Sharp is 24.000 in long and rifled 1 turn in 12.00 in, with a .210 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 21 Sharp 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.
21 Sharp vs 22 Hornet: 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 | 21 Sharp | 22 Hornet |
|---|---|---|
| Maximum average pressure | 24,000 psi | 49,000 psi |
| Standard test barrel length | 24.000 in | 24.000 in |
| Test barrel twist rate | 1 turn in 12.00 in | 1 turn in 16.00 in |
| Test barrel groove diameter | .210 in | .222 in |
| Lightest reference load | 25 gr — 1,725 fps / 165 ft-lb | 30 gr — 3,150 fps / 661 ft-lb |
| Heaviest reference load | 25 gr — 1,725 fps / 165 ft-lb | 35 gr — 3,040 fps / 718 ft-lb |
SAAMI standardises the 21 Sharp at 24,000 psi and the 22 Hornet at 49,000 psi, so the 21 Sharp runs 25,000 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 12.00 in for the 21 Sharp; 24.000 in, 1 turn in 16.00 in for the 22 Hornet), 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 Hornet ammo.
21 Sharp ballistics questions
What is the maximum pressure of the 21 Sharp?
ANSI/SAAMI Z299.1 sets the maximum average pressure for the 21 Sharp at 24,000 psi.
What twist rate and barrel length does SAAMI use for the 21 Sharp?
SAAMI’s standard test barrel for the 21 Sharp is 24.000 in long and rifled 1 turn in 12.00 in. Your own firearm may differ.
Is the 21 Sharp more powerful than the 22 Hornet?
SAAMI lists no bullet weight in common for the two, so there is no like-for-like row. Its highest computed reference energy is 165 ft-lb for the 21 Sharp (25 grains) and 718 ft-lb for the 22 Hornet.
What is the effective range of the 21 Sharp?
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 21 Sharp 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 21 Sharp ammunition from Winchester. Browse the full 21 Sharp ammo range.
