The 300 HAM’R is a centerfire rifle cartridge standardised by SAAMI in ANSI/SAAMI Z299.4. SAAMI sets its maximum average pressure at 57,500 psi, and measures its reference velocities in a 16.000 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 300 HAM’R with the 300 AAC BLACKOUT on the same basis.
300 Ham’r 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 |
|---|---|---|
| 125 gr | 2,450 fps | 1,666 ft-lb |
| 130 gr | 2,425 fps | 1,697 ft-lb |
What the numbers mean for a shot
SAAMI lists two reference bullet weights for the 300 HAM’R, 125 and 130 grains. The lighter, 125 grains, is listed at 2,450 fps, which computes to 1,666 ft-lb. The heavier, 130 grains, is listed at 2,425 fps, which computes to 1,697 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 300 Ham’r ammo range lists whatever its maker publishes for that item.
Twist rate, chamber and pressure
SAAMI’s standard test barrel for the 300 HAM’R is 16.000 in long and rifled 1 turn in 12.00 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. SAAMI measures the 300 HAM’R in a 16.000 in test barrel, not the 24.000 in used for most rifle cartridges, so its reference velocities cannot be set beside theirs without allowing for the barrel. The maximum average pressure is 57,500 psi. Fire 300 HAM’R 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 Ham’r vs 300 Blackout: 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 HAM’R | 300 AAC BLACKOUT |
|---|---|---|
| Maximum average pressure | 57,500 psi | 55,000 psi |
| Standard test barrel length | 16.000 in | 16.000 in |
| Test barrel twist rate | 1 turn in 12.00 in | 1 turn in 8.00 in |
| Test barrel groove diameter | .308 in | .308 in |
| Lightest reference load | 125 gr — 2,450 fps / 1,666 ft-lb | 90 gr — 2,500 fps / 1,249 ft-lb |
| A weight both list | 125 gr — 2,450 fps / 1,666 ft-lb | 125 gr — 2,185 fps / 1,325 ft-lb |
| Heaviest reference load | 130 gr — 2,425 fps / 1,697 ft-lb | 220 gr — 1,020 fps / 508 ft-lb |
SAAMI standardises the 300 HAM’R at 57,500 psi and the 300 AAC BLACKOUT at 55,000 psi, so the 300 HAM’R runs 2,500 psi higher. At 125 grains, a weight both list, SAAMI’s 300 HAM’R reference velocity is 2,450 fps (1,666 ft-lb computed), against 2,185 fps (1,325 ft-lb) for the 300 AAC BLACKOUT. On that row the 300 HAM’R carries the more energy. Their standard test barrels differ (16.000 in, 1 turn in 12.00 in for the 300 HAM’R; 16.000 in, 1 turn in 8.00 in for the 300 AAC BLACKOUT), 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: 300 Blackout ammo.
300 Ham’r ballistics questions
What is the maximum pressure of the 300 HAM’R?
ANSI/SAAMI Z299.4 sets the maximum average pressure for the 300 HAM’R at 57,500 psi.
What twist rate and barrel length does SAAMI use for the 300 HAM’R?
SAAMI’s standard test barrel for the 300 HAM’R is 16.000 in long and rifled 1 turn in 12.00 in. Your own rifle may differ.
What bullet weights does SAAMI list for the 300 HAM’R?
SAAMI lists 2 reference weights, from 125 to 130 grains: 125 and 130.
Is the 300 HAM’R more powerful than the 300 AAC BLACKOUT?
Power is not a SAAMI measure, but reference muzzle energy is a fair proxy. At 125 grains, a weight both list, SAAMI’s 300 HAM’R reference velocity is 2,450 fps (1,666 ft-lb computed), against 2,185 fps (1,325 ft-lb) for the 300 AAC BLACKOUT.
What is the effective range of the 300 HAM’R?
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 300 HAM’R 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 300 Ham’r ammunition from Wilson Combat and SIG SAUER. Browse the full 300 Ham’r ammo range.
