The 45 Automatic is a centerfire handgun cartridge standardised by SAAMI in ANSI/SAAMI Z299.3. SAAMI sets its maximum average pressure at 21,000 psi, and measures its reference velocities in a 5.000 in standard test barrel rifled 1 turn in 16.00 in, left hand. This guide sets out SAAMI’s published reference velocity for each bullet weight, computes the muzzle energy each one carries, and compares the 45 Automatic with the 9mm Luger on the same basis.
45 ACP 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 |
|---|---|---|
| 120 gr | 1,200 fps | 384 ft-lb |
| 155 gr | 1,125 fps | 436 ft-lb |
| 165 gr | 1,065 fps | 415 ft-lb |
| 170 gr | 1,050 fps | 416 ft-lb |
| 175 gr | 1,020 fps | 404 ft-lb |
| 185 gr | 770–1,100 fps | 244–497 ft-lb |
| 200 gr | 885 fps | 348 ft-lb |
| 220 gr | 775 fps | 293 ft-lb |
| 230 gr | 830–915 fps | 352–427 ft-lb |
What the numbers mean for a shot
SAAMI lists 9 reference bullet weights for the 45 Automatic, from 120 to 230 grains. The lightest, 120 grains, is listed at 1,200 fps, which computes to 384 ft-lb. The heaviest, 230 grains, is listed at 830–915 fps, which computes to 352–427 ft-lb. The most energetic reference load is the 185-grain at 1,100 fps: 497 ft-lb computed.
SAAMI lists more than one reference velocity for 185 and 230 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 45 ACP ammo range lists whatever its maker publishes for that item.
Barrel, chamber and pressure
SAAMI’s standard test barrel for the 45 Automatic is 5.000 in long and rifled 1 turn in 16.00 in, left hand, with a .450 in groove diameter. That is the barrel every reference velocity above was measured in, not a statement about your handgun: handgun barrels vary widely in length, and a shorter barrel gives lower velocity. The maximum average pressure is 21,000 psi. Fire 45 Automatic 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. SAAMI also standardises a +P level for the 45 Automatic, at 23,000 psi. +P ammunition is loaded to a higher pressure and should be fired only in a firearm its maker states is rated for it.
45 ACP vs 9mm: 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 | 45 Automatic | 9mm Luger |
|---|---|---|
| Maximum average pressure | 21,000 psi | 35,000 psi |
| Maximum average pressure, +P | 23,000 psi | 38,500 psi |
| Standard test barrel length | 5.000 in | 4.000 in |
| Test barrel twist rate | 1 turn in 16.00 in, left hand | 1 turn in 10.00 in |
| Test barrel groove diameter | .450 in | .3550 in |
| Lightest reference load | 120 gr — 1,200 fps / 384 ft-lb | 88 gr — 1,500 fps / 440 ft-lb |
| Heaviest reference load | 230 gr — 830–915 fps / 352–427 ft-lb | 150 gr — 900 fps / 270 ft-lb |
SAAMI standardises the 45 Automatic at 21,000 psi and the 9mm Luger at 35,000 psi, so the 45 Automatic runs 14,000 psi lower. SAAMI lists no bullet weight in common for the two, so there is no like-for-like velocity row to compare. Their standard test barrels differ (5.000 in, 1 turn in 16.00 in, left hand for the 45 Automatic; 4.000 in, 1 turn in 10.00 in for the 9mm Luger), 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: 9mm ammo.
45 ACP ballistics questions
What is the maximum pressure of the 45 Automatic?
ANSI/SAAMI Z299.3 sets the maximum average pressure for the 45 Automatic at 21,000 psi.
What twist rate and barrel length does SAAMI use for the 45 Automatic?
SAAMI’s standard test barrel for the 45 Automatic is 5.000 in long and rifled 1 turn in 16.00 in, left hand. Your own handgun may differ.
What bullet weights does SAAMI list for the 45 Automatic?
SAAMI lists 9 reference weights, from 120 to 230 grains: 120, 155, 165, 170, 175, 185, 200, 220 and 230.
Is the 45 Automatic more powerful than the 9mm Luger?
SAAMI lists no bullet weight in common for the two, so there is no like-for-like row. Its highest computed reference energy is 497 ft-lb for the 45 Automatic (185 grains) and 440 ft-lb for the 9mm Luger.
What is the +P pressure limit for the 45 Automatic?
SAAMI standardises a +P level for the 45 Automatic at 23,000 psi, against 21,000 psi for standard-pressure ammunition. +P ammunition should be fired only in a firearm its maker states is rated for it.
What is the effective range of the 45 Automatic?
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 45 ACP ammunition from Federal, Winchester, Remington, Buffalo Bore, Hornady and Underwood. Browse the full 45 ACP ammo range.
