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ARMAG

Search matches names, aliases and the text of every page. An arm found by its service designation is found by its alias, not its title.

.357 Magnum

Introduced 1935Elmer Keith, Phillip B. Sharpe and Douglas B. WessonCIP standard

Also known as 9×33mmR — the same cartridge under different names, all of which find this page.

Dimensions and pressure

Generated from the schema, like every specification table on this site, so a figure recorded on this entry cannot be missing from the table.

Identity
Designed by
Elmer Keith, Phillip B. Sharpe and Douglas B. Wesson
Introduced
1935
Production
not recorded
Standards body
C.I.P.
Case type
Rimmed
Case shape
Straight
Dimensions
Bullet diameter
9.12 mm0.3591 insource

C.I.P. G1, maximum bullet diameter.

Bore diameter
not recorded
Case length
32.77 mm1.290 insource

C.I.P. L3, maximum case length.

Overall length
40.39 mm1.590 insource

C.I.P. L6, maximum cartridge overall length.

Rim diameter
11.18 mm0.4402 insource

C.I.P. R1.

Neck diameter
9.63 mm0.3791 insource

C.I.P. H2.

Base diameter
9.63 mm0.3791 insource

C.I.P. P1.

Pressure
Maximum pressure
300 MPa43,511 psisource

C.I.P. Pmax 3000 bar; 1 bar = 0.1 MPa exactly.

Pressure standard
C.I.P.

SAAMI and C.I.P. measure pressure differently and their figures are not interchangeable, which is why the body is always named beside the figure.

Loads

Velocity is recorded per barrel length as published. A gun page interpolates between these points and never projects beyond them.

Federal 125 gr jacketed hollow point

Federal

Bullet mass
8.1 g125.0 grsource

Published as 125 gr; 1 gr = 0.06479891 g exactly.

Cartridge mass
not recorded
Bullet type
JHP
G1 BC
not recorded
G7 BC
not recorded
Sourced velocity by barrel length
BarrelVelocity
101.6 mm4.000 in442 m/s1,450 fps

Federal 158 gr jacketed hollow point

Federal

Bullet mass
10.24 g158.0 grsource

Published as 158 gr; 1 gr = 0.06479891 g exactly.

Cartridge mass
not recorded
Bullet type
JHP
G1 BC
not recorded
G7 BC
not recorded
Sourced velocity by barrel length
BarrelVelocity
101.6 mm4.000 in378 m/s1,240 fps

Chambered in

Computed from every entry that lists this cartridge. Nothing here is hand-maintained.

Gallery

A .357 Magnum cartridge on orange graph paper, its straight case ending in a narrow rim.

Image credit

Title
File:Cartridge .357 Magnum.jpg
Author
Grasyl(attribution required)
Licence
CC BY-SA 4.0
Source
https://commons.wikimedia.org/wiki/File:Cartridge_.357_Magnum.jpg
A .357 Magnum round on graph paper.

Detail

The .38 Special case lengthened by three millimetres and loaded to twice the pressure. The extra length is deliberate and structural: a .357 will not chamber in a .38, so the higher-pressure round cannot be fired in a gun not built for it, and a .38 will chamber and fire in a .357 quite happily.

Elmer Keith had been loading .38 Special beyond its limits for years and breaking guns doing it; Smith & Wesson’s contribution in 1935 was a frame heavy enough to contain the result and a case that could not be put in a lighter one. C.I.P. rates it at 300 MPa, double the .38’s 150.

The velocities below are from a four-inch vented barrel. A six- or eight-inch revolver gains a great deal over that, and a lever-action carbine in the same chambering gains more again — which this site will show only where a source states the barrel it measured.

References

  1. C.I.P. TDCC datasheet — 357 Magnum · 2006-06-14 · read 2026-08-31
  2. .357 Magnum · 1368987349 · read 2026-08-31

Last verified 2026-08-31 · review status: agent-populated