The 357 Magnum is a centerfire handgun cartridge standardised by SAAMI in ANSI/SAAMI Z299.3. SAAMI sets its maximum average pressure at 35,000 psi, and publishes its reference velocities for both a vented barrel and the standard test barrel. This guide sets out SAAMI’s published reference velocity for each bullet weight, computes the muzzle energy each one carries, and compares the 357 Magnum with the 38 Special on the same basis.
357 Magnum ballistics chart: SAAMI reference data
SAAMI publishes nominal mean instrumental velocities for each reference bullet weight, measured at 15 feet from a vented barrel and from the standard test barrel, and marks a figure it has not established. It does not publish energy, so the ft-lb figures are 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 | Vented-barrel velocity / computed energy | Test-barrel velocity / computed energy |
|---|---|---|
| 101 gr | 1,235 fps / 342 ft-lb | 1,650 fps / 610 ft-lb |
| 110 gr | 1,270 fps / 394 ft-lb | 1,650 fps / 665 ft-lb |
| 125 gr | 1,220–1,425 fps / 413–564 ft-lb | 1,500–1,875 fps / 624–976 ft-lb |
| 130 gr | 1,300 fps / 488 ft-lb | 1,475 fps / 628 ft-lb |
| 135 gr | Not established | 1,260 fps / 476 ft-lb |
| 140 gr | 1,330 fps / 550 ft-lb | 1,440–1,750 fps / 644–952 ft-lb |
| 145 gr | 1,270 fps / 519 ft-lb | 1,670 fps / 898 ft-lb |
| 158 gr | 1,220 fps / 522 ft-lb | 1,545–1,600 fps / 837–898 ft-lb |
| 165 gr | Not established | 1,510 fps / 835 ft-lb |
| 180 gr | 1,000 fps / 400 ft-lb | 1,350–1,400 fps / 728–783 ft-lb |
What the numbers mean for a shot
SAAMI lists 10 reference bullet weights for the 357 Magnum, from 101 to 180 grains. The lightest, 101 grains, is listed at 1,235 fps in a vented barrel (342 ft-lb computed) and 1,650 fps in the test barrel (610 ft-lb computed). The heaviest, 180 grains, is listed at 1,000 fps in a vented barrel (400 ft-lb computed) and 1,350–1,400 fps in the test barrel (728–783 ft-lb computed). The most energetic reference load is the 125-grain at 1,875 fps in the test barrel: 976 ft-lb computed.
SAAMI lists more than one reference velocity for 125, 140, 158 and 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 357 Magnum ammo range lists whatever its maker publishes for that item.
Barrel, chamber and pressure
A revolver loses some gas, and with it velocity, at the gap between cylinder and barrel, which is why SAAMI publishes a vented-barrel velocity for revolver cartridges beside the test-barrel one. SAAMI notes that the vented-barrel figures “are provided for information only” and that vented test barrels are used for the establishment of catalog velocity values for cartridges normally chambered in revolvers. Your own revolver’s barrel length will move the numbers again. The maximum average pressure is 35,000 psi. Fire 357 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.
357 Magnum vs 38 Special: 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 | 357 Magnum | 38 Special |
|---|---|---|
| Maximum average pressure | 35,000 psi | 17,000 psi |
| Maximum average pressure, +P | No +P standard | 20,000 psi |
| Standard test barrel length | Revolver test barrel (see SAAMI drawing) | Revolver test barrel (see SAAMI drawing) |
| Test barrel twist rate | 1 turn in 18.75 in | 1 turn in 18.75 in |
| Test barrel groove diameter | .355 in | .355 in |
| Lightest reference load | 101 gr — 1,650 fps / 610 ft-lb | 90 gr — 1,180 fps / 278 ft-lb |
| A weight both list | 130 gr — 1,475 fps / 628 ft-lb | 130 gr — 775–1,040 fps / 173–312 ft-lb |
| Heaviest reference load | 180 gr — 1,350–1,400 fps / 728–783 ft-lb | 200 gr — 780 fps / 270 ft-lb |
SAAMI standardises the 357 Magnum at 35,000 psi and the 38 Special at 17,000 psi, so the 357 Magnum runs 18,000 psi higher. At 130 grains, a weight both list, SAAMI’s 357 Magnum reference velocity is 1,475 fps (628 ft-lb computed), against up to 1,040 fps (312 ft-lb) for the 38 Special. On that row the 357 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: 38 Special ammo.
357 Magnum ballistics questions
What is the maximum pressure of the 357 Magnum?
ANSI/SAAMI Z299.3 sets the maximum average pressure for the 357 Magnum at 35,000 psi.
What twist rate does SAAMI use for the 357 Magnum?
SAAMI’s test barrel drawing for the 357 Magnum shows rifling of 1 turn in 18.75 in. Revolver barrel lengths vary widely, so your own revolver may differ.
What bullet weights does SAAMI list for the 357 Magnum?
SAAMI lists 10 reference weights, from 101 to 180 grains: 101, 110, 125, 130, 135, 140, 145, 158, 165 and 180.
Is the 357 Magnum more powerful than the 38 Special?
Power is not a SAAMI measure, but reference muzzle energy is a fair proxy. At 130 grains, a weight both list, SAAMI’s 357 Magnum reference velocity is 1,475 fps (628 ft-lb computed), against up to 1,040 fps (312 ft-lb) for the 38 Special.
What is the effective range of the 357 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 357 Magnum drop at 100 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 357 Magnum ammunition from Buffalo Bore, Remington, Federal, Grizzly Cartridge Company, Underwood and Hornady. Browse the full 357 Magnum ammo range.
