Practice & target
Full-metal-jacket, plated, lead, and wadcutter bullets describe different constructions. Grain weight is projectile mass; it does not state a powder charge or guarantee recoil.
THE CARTRIDGE LIBRARY · PISTOL
.357 SIG
A bottleneck semiautomatic-pistol cartridge using a nominal 9mm-class bullet. The .357 name refers to a design objective rather than a shared case with .357 Magnum.
2A Ledger reference desk · Sources checked October 18, 2026
Read the dimensions
- Overall · min–max
- 1.100–1.140 in
27.940–28.956 mm - Case length · max
- 0.865 in
21.971 mm - Bullet maximum
- 0.3555 in
9.030 mm - Rim diameter · max
- 0.424 in
10.770 mm
Know the exact name
At a glance
- Cartridge family
- Pistol
- Bullet specification
- 0.3555 in / 9.030 mmBullet maximum
- Factory examples
- 4 loadsSelected, sourced examples below
- Weight in cited examples
- 125–147 grGrains measure mass, not powder charge
.357 SIG is identified by its complete cartridge designation. The resource-table alternative is 357 SIG. A caliber number, bullet diameter, or family resemblance on its own does not identify ammunition compatibility.
It is not .357 Magnum ammunition. A similar name or bullet weight is not evidence of compatible chambers.
Dimensions: open the exact dimensional drawing ↗. The displayed number is bullet maximum, rather than an assertion that every manufactured projectile or barrel has this exact diameter.
Origins & evolution
Background & development
Federal and SIG introduced the .357 SIG in early 1994, during the American police transition from service revolvers to automatic pistols. The project aimed to approach the performance associated with a 125-grain .357 Magnum service load in a compact self-loading handgun cartridge. That was a design objective tied to a particular bullet and role, not a claim that every load in the two cartridges performs identically.
The resulting bottleneck case and .355-inch bullet gave the SIG its own geometry and ammunition requirements. Its name referred to the performance class the developers wanted to pursue, rather than to the actual bullet diameter used by the .357 Magnum. This makes it a particularly useful example of why cartridge names are historical identifiers. The .357 SIG belongs to the 1990s development of purpose-built police-pistol ammunition, with a different origin and platform from the older Magnum whose name helped describe its ambition.
Historical sources: Sierra: .357 SIG cartridge history ↗
Construction changes the story
Loads, variations & specialty offerings
Expanding factory bullets
JHP, XTP, FTX, HST, and similar product names refer to particular designs. Muzzle energy alone does not show expansion, penetration, or reliability in a particular firearm.
Specialty load families
Reduced-recoil, subsonic, monolithic, and heavier-bullet offerings are product-specific. A +P marking is a pressure category where standardized, not simply a heavier bullet. Follow the maker’s exact product and firearm guidance.
In the cited .357 SIG examples, bullet weights are 125, 135, 147 grains. These are the weights actually present in this source selection, not a claim that every possible loading is listed.
Bullet construction background: Hornady: anatomy of a bullet ↗. Exact product descriptions and velocities are cited in the factory table.
From the factory catalog
125 grains
1,350 fps
FMJ
135 grains
1,225 fps
FlexLock®
147 grains
1,225 fps
XTP®
Compare all 4 cited factory load records
| Maker / product | Bullet mass | Published construction | Muzzle velocity | Test barrel | Source |
|---|---|---|---|---|---|
| FederalAE357S2 | 125 gr 8.10 g | FMJ | 1,350 fps 411 m/s | 4 in | Federal · PDF p. 61 ↗ |
| FederalP357SHST1S | 125 gr 8.10 g | HST | 1,360 fps 415 m/s | 4 in | Federal · PDF p. 60 ↗ |
| Hornady91296 | 135 gr 8.75 g | FlexLock® | 1,225 fps 373 m/s | 4 in | Hornady · PDF p. 191 ↗ |
| Hornady9131 | 147 gr 9.53 g | XTP® | 1,225 fps 373 m/s | 4 in | Hornady · PDF p. 191 ↗ |
Explore the published data
Ballistics you can inspect
Select a legend entry to add or remove its line. Hover or tap a plotted point, or use the position slider. With the graph focused, arrow keys move the inspector. Solid dots identify source points; dashed connectors show estimates between them. Load construction, pressure category, and test setup can differ even at the same grain weight.
Read the original values as accessible tables
.357 SIG: velocity by barrel length
| Exact load | Source | Published points |
|---|---|---|
| Cor Bon 115 gr. JHP | BBTI | 2: 1222; 3: 1373; 4: 1491; 5: 1578; 6: 1588; 7: 1641; 8: 1654; 9: 1694; 10: 1708; 11: 1721; 12: 1751; 13: 1759; 14: 1764; 15: 1794; 16: 1768; 17: 1781; 18: 1770 |
| Cor Bon 125 gr. JHP | BBTI | 2: 1173; 3: 1326; 4: 1468; 5: 1537; 6: 1552; 7: 1599; 8: 1627; 9: 1669; 10: 1690; 11: 1699; 12: 1699; 13: 1721; 14: 1747; 15: 1746; 16: 1723; 17: 1736; 18: 1729 |
| Cor Bon 125 gr. DPX | BBTI | 2: 1125; 3: 1237; 4: 1317; 5: 1402; 6: 1395; 7: 1429; 8: 1451; 9: 1468; 10: 1474; 11: 1495; 12: 1514; 13: 1521; 14: 1518; 15: 1545; 16: 1500; 17: 1526; 18: 1508 |
| Federal Premium 125 gr. JHP | BBTI | 2: 1145; 3: 1319; 4: 1426; 5: 1501; 6: 1531; 7: 1585; 8: 1612; 9: 1636; 10: 1658; 11: 1665; 12: 1683; 13: 1704; 14: 1723; 15: 1733; 16: 1723; 17: 1720; 18: 1722 |
.357 SIG: factory velocity downrange
| Exact load | Source | Published points |
|---|---|---|
| 125 gr Federal FMJ | Federal | 0: 1350; 25: 1266; 50: 1192; 75: 1130; 100: 1078 |
| 135 gr Hornady FlexLock® | Hornady | 0: 1225; 50: 1112; 100: 1031 |
| 147 gr Hornady XTP® | Hornady | 0: 1225; 50: 1132; 100: 1060 |
| 125 gr Federal HST | Federal | 0: 1360; 25: 1275; 50: 1200; 75: 1136; 100: 1083 |
How to interpret the comparison
Changing bullet weight also often changes bullet design and propellant choice. Two curves are comparisons of the listed products, not a controlled experiment proving that bullet weight alone caused the difference. Catalog downrange points are projections under the maker’s conditions; barrel-study points are recorded observations in the study firearm.
Direct answers
Common questions
What is .357 SIG?
A bottleneck semiautomatic-pistol cartridge using a nominal 9mm-class bullet. The .357 name refers to a design objective rather than a shared case with .357 Magnum.
What diameter does .357 SIG use?
The cited dimensional standard lists 0.3555 inches (9.030 mm), bullet maximum. This drawing convention is different from a casual caliber nickname.
Are similarly named cartridges interchangeable?
It is not .357 Magnum ammunition. A similar name or bullet weight is not evidence of compatible chambers.
Are the graph values measured or estimated?
BBTI points come from the cited cut-down barrel study. The downrange view uses the exact manufacturer catalog records shown in the source table. Dashed connectors and intermediate inspector values use linear interpolation between the displayed source points. Calculated energy uses the listed bullet mass and velocity.
Does higher energy mean the best load?
Energy is calculated from mass and velocity. It does not establish accuracy, expansion, penetration, pattern density, recoil, or suitability for a particular firearm. Use the exact product documentation and firearm manual.
Looking for SIG’s military 6.8×51 mm rifle cartridge? Read the .277 SIG FURY and 6.8×51 mm guide →.
Trace the facts
Sources & methodology
Skives & petals: read the jacket construction →
Compiled by 2A Ledger from the linked standards, manufacturer publications, and identified test records. Checked October 18, 2026. Historical tests and older catalogs retain their original dates; a listing here does not establish current availability.
- SAAMI: dimensional drawing · PDF p. 46 ↗
- Sierra: .357 SIG cartridge background ↗
- Federal · PDF p. 61 ↗
- Federal · PDF p. 60 ↗
- Hornady · PDF p. 191 ↗
- Ballistics by the Inch: archived measured barrel data (2020 archive) ↗
- BBTI: study index and source records ↗
Diameter figures preserve the cited drawing convention. Inch–millimeter conversion uses exactly 25.4 mm per inch. Factory specifications describe the maker’s test setup; your firearm, ammunition lot, temperature, and measuring method can produce different results. This is an educational factory-ammunition reference, not a reloading manual.