The 7mm Weatherby Magnum is a centerfire rifle cartridge standardised by SAAMI in ANSI/SAAMI Z299.4. SAAMI sets its maximum average pressure at 65,000 psi, and measures its reference velocities in a 24.000 in standard test barrel rifled 1 turn in 10.00 in. This guide sets out SAAMI’s published reference velocity for each bullet weight, computes the muzzle energy each one carries, and compares the 7mm Weatherby Magnum with the 7mm Remington Magnum on the same basis.
7mm Weatherby Magnum 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 |
|---|---|---|
| 140 gr | 3,165 fps | 3,113 ft-lb |
| 160 gr | 3,100 fps | 3,414 ft-lb |
| 175 gr | 2,840 fps | 3,134 ft-lb |
What the numbers mean for a shot
SAAMI lists 3 reference bullet weights for the 7mm Weatherby Magnum, from 140 to 175 grains. The lightest, 140 grains, is listed at 3,165 fps, which computes to 3,113 ft-lb. The heaviest, 175 grains, is listed at 2,840 fps, or 3,134 ft-lb. The most energetic reference load is the 160-grain at 3,100 fps: 3,414 ft-lb computed.
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 7mm Weatherby Magnum ammo range lists whatever its maker publishes for that item.
Twist rate, chamber and pressure
SAAMI’s standard test barrel for the 7mm Weatherby Magnum is 24.000 in long and rifled 1 turn in 10.00 in, with a .284 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 65,000 psi. Fire 7mm Weatherby 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.
7mm Weatherby Magnum vs 7mm Rem Mag: 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 | 7mm Weatherby Magnum | 7mm Remington Magnum |
|---|---|---|
| Maximum average pressure | 65,000 psi | 61,000 psi |
| Standard test barrel length | 24.000 in | 24.000 in |
| Test barrel twist rate | 1 turn in 10.00 in | 1 turn in 9.50 in |
| Test barrel groove diameter | .284 in | .2837 in |
| Lightest reference load | 140 gr — 3,165 fps / 3,113 ft-lb | 125 gr — 3,290 fps / 3,004 ft-lb |
| A weight both list | 175 gr — 2,840 fps / 3,134 ft-lb | 175 gr — 2,750–2,850 fps / 2,938–3,156 ft-lb |
SAAMI standardises the 7mm Weatherby Magnum at 65,000 psi and the 7mm Remington Magnum at 61,000 psi, so the 7mm Weatherby Magnum runs 4,000 psi higher. At 175 grains, a weight both list, SAAMI’s 7mm Weatherby Magnum reference load is 2,840 fps and 3,134 ft-lb computed, against 2,850 fps and 3,156 ft-lb for the 7mm Remington Magnum. On that row the 7mm Remington Magnum carries the more energy. Their standard test barrels differ (24.000 in, 1 turn in 10.00 in for the 7mm Weatherby Magnum; 24.000 in, 1 turn in 9.50 in for the 7mm Remington Magnum), 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: 7mm Rem Mag ammo.
7mm Weatherby Magnum ballistics questions
What is the maximum pressure of the 7mm Weatherby Magnum?
ANSI/SAAMI Z299.4 sets the maximum average pressure for the 7mm Weatherby Magnum at 65,000 psi.
What twist rate and barrel length does SAAMI use for the 7mm Weatherby Magnum?
SAAMI’s standard test barrel for the 7mm Weatherby Magnum is 24.000 in long and rifled 1 turn in 10.00 in. Your own rifle may differ, and a twist slower than a long, heavy bullet needs will not stabilise it.
What bullet weights does SAAMI list for the 7mm Weatherby Magnum?
SAAMI lists 3 reference weights, from 140 to 175 grains: 140, 160 and 175.
Is the 7mm Weatherby Magnum more powerful than the 7mm Remington Magnum?
Power is not a SAAMI measure, but reference muzzle energy is a fair proxy. At 175 grains, a weight both list, SAAMI’s 7mm Weatherby Magnum reference load is 2,840 fps and 3,134 ft-lb computed, against 2,850 fps and 3,156 ft-lb for the 7mm Remington Magnum.
How much does the 7mm Weatherby 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.
What is the effective range of the 7mm Weatherby 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.
Where to buy these loads
Hilltop Armory carries 7mm Weatherby Magnum ammunition from Hornady, Federal, Norma, Nosler and CorBon. Browse the full 7mm Weatherby Magnum ammo range.
