The 450 Bushmaster is a centerfire rifle cartridge standardised by SAAMI in ANSI/SAAMI Z299.4. SAAMI sets its maximum average pressure at 38,500 psi, and measures its reference velocities in a 24.000 in standard test barrel rifled 1 turn in 24 in. This guide sets out SAAMI’s published reference velocity for each bullet weight, computes the muzzle energy each one carries, and compares the 450 Bushmaster with the 45-70 Government on the same basis.
450 Bushmaster 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 |
|---|---|---|
| 250 gr | 2,250 fps | 2,810 ft-lb |
| 260 gr | 2,150 fps | 2,668 ft-lb |
| 300 gr | 1,900 fps | 2,404 ft-lb |
| 395 gr | 1,050 fps | 967 ft-lb |
What the numbers mean for a shot
SAAMI lists 4 reference bullet weights for the 450 Bushmaster, from 250 to 395 grains. The lightest, 250 grains, is listed at 2,250 fps, which computes to 2,810 ft-lb. The heaviest, 395 grains, is listed at 1,050 fps, or 967 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 450 Bushmaster ammo range lists whatever its maker publishes for that item.
Twist rate, chamber and pressure
SAAMI’s standard test barrel for the 450 Bushmaster is 24.000 in long and rifled 1 turn in 24 in, with a .450 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 38,500 psi. Fire 450 Bushmaster 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.
450 Bushmaster vs 45-70: 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 | 450 Bushmaster | 45-70 Government |
|---|---|---|
| Maximum average pressure | 38,500 psi | 28,000 psi |
| Standard test barrel length | 24.000 in | 24.000 in |
| Test barrel twist rate | 1 turn in 24 in | 1 turn in 20.00 in |
| Test barrel groove diameter | .450 in | .456 in |
| Lightest reference load | 250 gr — 2,250 fps / 2,810 ft-lb | 250 gr — 2,025 fps / 2,276 ft-lb |
| A weight both list | 300 gr — 1,900 fps / 2,404 ft-lb | 300 gr — 1,830–1,880 fps / 2,230–2,354 ft-lb |
| Heaviest reference load | 395 gr — 1,050 fps / 967 ft-lb | 405 gr — 1,150–1,600 fps / 1,189–2,302 ft-lb |
SAAMI standardises the 450 Bushmaster at 38,500 psi and the 45-70 Government at 28,000 psi, so the 450 Bushmaster runs 10,500 psi higher. At 300 grains, a weight both list, SAAMI’s 450 Bushmaster reference load is 1,900 fps and 2,404 ft-lb computed, against 1,880 fps and 2,354 ft-lb for the 45-70 Government. On that row the 450 Bushmaster carries the more energy. Their standard test barrels differ (24.000 in, 1 turn in 24 in for the 450 Bushmaster; 24.000 in, 1 turn in 20.00 in for the 45-70 Government), 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: 45-70 ammo.
450 Bushmaster ballistics questions
What is the maximum pressure of the 450 Bushmaster?
ANSI/SAAMI Z299.4 sets the maximum average pressure for the 450 Bushmaster at 38,500 psi.
What twist rate and barrel length does SAAMI use for the 450 Bushmaster?
SAAMI’s standard test barrel for the 450 Bushmaster is 24.000 in long and rifled 1 turn in 24 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 450 Bushmaster?
SAAMI lists 4 reference weights, from 250 to 395 grains: 250, 260, 300 and 395.
Is the 450 Bushmaster more powerful than the 45-70 Government?
Power is not a SAAMI measure, but reference muzzle energy is a fair proxy. At 300 grains, a weight both list, SAAMI’s 450 Bushmaster reference load is 1,900 fps and 2,404 ft-lb computed, against 1,880 fps and 2,354 ft-lb for the 45-70 Government.
How much does the 450 Bushmaster 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 450 Bushmaster?
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 450 Bushmaster ammunition from Buffalo Bore, Hornady, Federal, Remington, Winchester and Barnes. Browse the full 450 Bushmaster ammo range.
