The 338 Norma Magnum is a centerfire rifle cartridge standardised by SAAMI in ANSI/SAAMI Z299.4. SAAMI sets its maximum average pressure at 62,500 psi, and measures its reference velocities in a 24.000 in standard test barrel rifled 1 turn in 9.25 in. This guide sets out SAAMI’s published reference velocity for each bullet weight, computes the muzzle energy each one carries, and compares the 338 Norma Magnum with the 338 Lapua Magnum on the same basis.
338 Norma 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 |
|---|---|---|
| 300 gr | 2,670 fps | 4,748 ft-lb |
What the numbers mean for a shot
SAAMI lists a single reference bullet weight for the 338 Norma Magnum: 300 grains, listed at 2,670 fps, which computes to 4,748 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 338 Norma Magnum ammo range lists whatever its maker publishes for that item.
Twist rate, chamber and pressure
SAAMI’s standard test barrel for the 338 Norma Magnum is 24.000 in long and rifled 1 turn in 9.25 in. 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 62,500 psi. Fire 338 Norma 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.
338 Norma Magnum vs 338 Lapua: 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 | 338 Norma Magnum | 338 Lapua Magnum |
|---|---|---|
| Maximum average pressure | 62,500 psi | 65,000 psi |
| Standard test barrel length | 24.000 in | 24.000 in |
| Test barrel twist rate | 1 turn in 9.25 in | 1 turn in 10.00 in |
| Test barrel groove diameter | Not read from the drawing | .338 in |
| Lightest reference load | 300 gr — 2,670 fps / 4,748 ft-lb | 250 gr — 2,950 fps / 4,830 ft-lb |
| A weight both list | 300 gr — 2,670 fps / 4,748 ft-lb | 300 gr — 2,620 fps / 4,572 ft-lb |
SAAMI standardises the 338 Norma Magnum at 62,500 psi and the 338 Lapua Magnum at 65,000 psi, so the 338 Norma Magnum runs 2,500 psi lower. At 300 grains, a weight both list, SAAMI’s 338 Norma Magnum reference velocity is 2,670 fps (4,748 ft-lb computed), against 2,620 fps (4,572 ft-lb) for the 338 Lapua Magnum. On that row the 338 Norma Magnum carries the more energy. Their standard test barrels differ (24.000 in, 1 turn in 9.25 in for the 338 Norma Magnum; 24.000 in, 1 turn in 10.00 in for the 338 Lapua 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: 338 Lapua ammo.
338 Norma Magnum ballistics questions
What is the maximum pressure of the 338 Norma Magnum?
ANSI/SAAMI Z299.4 sets the maximum average pressure for the 338 Norma Magnum at 62,500 psi.
What twist rate and barrel length does SAAMI use for the 338 Norma Magnum?
SAAMI’s standard test barrel for the 338 Norma Magnum is 24.000 in long and rifled 1 turn in 9.25 in. Your own rifle may differ.
Is the 338 Norma Magnum more powerful than the 338 Lapua Magnum?
Power is not a SAAMI measure, but reference muzzle energy is a fair proxy. At 300 grains, a weight both list, SAAMI’s 338 Norma Magnum reference velocity is 2,670 fps (4,748 ft-lb computed), against 2,620 fps (4,572 ft-lb) for the 338 Lapua Magnum.
What is the effective range of the 338 Norma 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 338 Norma 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 338 Norma Magnum ammunition from Black Hills Ammunition, CorBon and Norma. Browse the full 338 Norma Magnum ammo range.
