The 264 Winchester Magnum is a centerfire rifle cartridge standardised by SAAMI in ANSI/SAAMI Z299.4. SAAMI sets its maximum average pressure at 64,000 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 264 Winchester Magnum with the 6.5 Precision Rifle Cartridge on the same basis.
264 Win Mag ballistics chart: SAAMI reference data
SAAMI publishes one nominal mean instrumental velocity for each reference bullet weight, measured at 15 feet from the standard test barrel. It does not publish energy, so the ft-lb column is computed. Where SAAMI lists more than one velocity for a weight, both ends of the span are shown.
Scroll the table sideways for the remaining columns.
| Bullet weight | Reference velocity | Computed muzzle energy |
|---|---|---|
| 100 gr | 3,300 fps | 2,418 ft-lb |
| 140 gr | 3,015 fps | 2,825 ft-lb |
What the numbers mean for a shot
SAAMI lists two reference bullet weights for the 264 Winchester Magnum, 100 and 140 grains. The lighter, 100 grains, is listed at 3,300 fps, which computes to 2,418 ft-lb. The heavier, 140 grains, is listed at 3,015 fps, which computes to 2,825 ft-lb.
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 264 Win Mag ammo range lists whatever its maker publishes for that item.
Twist rate, chamber and pressure
SAAMI’s standard test barrel for the 264 Winchester Magnum is 24.000 in long and rifled 1 turn in 9.00 in, with a .264 in groove diameter. That is the barrel every reference velocity above was measured in, not a statement about your rifle: a shorter production barrel will usually give lower velocity, and a twist slower than a bullet needs will not stabilise it. The maximum average pressure is 64,000 psi. Fire 264 Winchester Magnum 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.
264 Win Mag vs 6.5 PRC: 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 | 264 Winchester Magnum | 6.5 Precision Rifle Cartridge |
|---|---|---|
| Maximum average pressure | 64,000 psi | 65,000 psi |
| Standard test barrel length | 24.000 in | 24.000 in |
| Test barrel twist rate | 1 turn in 9.00 in | 1 turn in 8.00 in |
| Test barrel groove diameter | .264 in | .264 in |
| Lightest reference load | 100 gr — 3,300 fps / 2,418 ft-lb | 147 gr — 2,900 fps / 2,745 ft-lb |
| Heaviest reference load | 140 gr — 3,015 fps / 2,825 ft-lb | 147 gr — 2,900 fps / 2,745 ft-lb |
SAAMI standardises the 264 Winchester Magnum at 64,000 psi and the 6.5 Precision Rifle Cartridge at 65,000 psi, so the 264 Winchester Magnum runs 1,000 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 9.00 in for the 264 Winchester Magnum; 24.000 in, 1 turn in 8.00 in for the 6.5 Precision Rifle Cartridge), 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: 6.5 PRC ammo.
264 Win Mag ballistics questions
What is the maximum pressure of the 264 Winchester Magnum?
ANSI/SAAMI Z299.4 sets the maximum average pressure for the 264 Winchester Magnum at 64,000 psi.
What twist rate and barrel length does SAAMI use for the 264 Winchester Magnum?
SAAMI’s standard test barrel for the 264 Winchester Magnum is 24.000 in long and rifled 1 turn in 9.00 in. Your own rifle may differ.
What bullet weights does SAAMI list for the 264 Winchester Magnum?
SAAMI lists 2 reference weights, from 100 to 140 grains: 100 and 140.
Is the 264 Winchester Magnum more powerful than the 6.5 Precision Rifle Cartridge?
SAAMI lists no bullet weight in common for the two, so there is no like-for-like row. Its highest computed reference energy is 2,825 ft-lb for the 264 Winchester Magnum (140 grains) and 2,745 ft-lb for the 6.5 Precision Rifle Cartridge.
What is the effective range of the 264 Winchester Magnum?
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 264 Winchester Magnum drop at 300 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 264 Win Mag ammunition from Nosler, DoubleTap Ammunition, HSM Ammunition and Remington. Browse the full 264 Win Mag ammo range.
