The 300 Remington Ultra 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 300 Remington Ultra Magnum with the 300 Winchester Magnum on the same basis.
300 RUM 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 |
|---|---|---|
| 150 gr | 2,910–3,440 fps | 2,820–3,941 ft-lb |
| 165 gr | 3,200–3,350 fps | 3,751–4,111 ft-lb |
| 180 gr | 2,960–3,225 fps | 3,501–4,156 ft-lb |
| 190 gr | 3,095 fps | 4,041 ft-lb |
| 200 gr | 3,025 fps | 4,063 ft-lb |
| 220 gr | 2,900 fps | 4,108 ft-lb |
What the numbers mean for a shot
SAAMI lists 6 reference bullet weights for the 300 Remington Ultra Magnum, from 150 to 220 grains. The lightest, 150 grains, is listed at 2,910–3,440 fps, which computes to 2,820–3,941 ft-lb. The heaviest, 220 grains, is listed at 2,900 fps, or 4,108 ft-lb. The most energetic reference load is the 180-grain at 3,225 fps: 4,156 ft-lb computed.
SAAMI lists more than one reference velocity for 150, 165, 180 grains. Its own note says this is because a weight can carry several introductions meeting different market needs, such as reduced-recoil loads, or because propellant and loading advances allowed higher velocities after the original load appeared.
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 300 RUM ammo range lists whatever its maker publishes for that item.
Twist rate, chamber and pressure
SAAMI’s standard test barrel for the 300 Remington Ultra Magnum is 24.000 in long and rifled 1 turn in 10.00 in, with a .308 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 300 Remington Ultra 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.
300 RUM vs 300 Win 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 | 300 Remington Ultra Magnum | 300 Winchester Magnum |
|---|---|---|
| Maximum average pressure | 65,000 psi | 64,000 psi |
| Standard test barrel length | 24.000 in | 24.000 in |
| Test barrel twist rate | 1 turn in 10.00 in | 1 turn in 10.00 in |
| Test barrel groove diameter | .308 in | .308 in |
| Lightest reference load | 150 gr — 2,910–3,440 fps / 2,820–3,941 ft-lb | 150 gr — 2,635–3,390 fps / 2,312–3,827 ft-lb |
| A weight both list | 190 gr — 3,095 fps / 4,041 ft-lb | 190 gr — 2,875 fps / 3,487 ft-lb |
| Heaviest reference load | 220 gr — 2,900 fps / 4,108 ft-lb | 220 gr — 2,665 fps / 3,469 ft-lb |
SAAMI standardises the 300 Remington Ultra Magnum at 65,000 psi and the 300 Winchester Magnum at 64,000 psi, so the 300 Remington Ultra Magnum runs 1,000 psi higher. At 190 grains, a weight both list, SAAMI’s 300 Remington Ultra Magnum reference load is 3,095 fps and 4,041 ft-lb computed, against 2,875 fps and 3,487 ft-lb for the 300 Winchester Magnum. On that row the 300 Remington Ultra Magnum carries the more energy.
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: 300 Win Mag ammo.
300 RUM ballistics questions
What is the maximum pressure of the 300 Remington Ultra Magnum?
ANSI/SAAMI Z299.4 sets the maximum average pressure for the 300 Remington Ultra Magnum at 65,000 psi.
What twist rate and barrel length does SAAMI use for the 300 Remington Ultra Magnum?
SAAMI’s standard test barrel for the 300 Remington Ultra 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 300 Remington Ultra Magnum?
SAAMI lists 6 reference weights, from 150 to 220 grains: 150, 165, 180, 190, 200 and 220.
Is the 300 Remington Ultra Magnum more powerful than the 300 Winchester Magnum?
Power is not a SAAMI measure, but reference muzzle energy is a fair proxy. At 190 grains, a weight both list, SAAMI’s 300 Remington Ultra Magnum reference load is 3,095 fps and 4,041 ft-lb computed, against 2,875 fps and 3,487 ft-lb for the 300 Winchester Magnum.
How much does the 300 Remington Ultra 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 300 Remington Ultra 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 300 RUM ammunition from DoubleTap Ammunition, Federal, Barnes, CorBon and HSM Ammunition. Browse the full 300 RUM ammo range.
