.300 WSM

Know the exact name

At a glance

Cartridge family

Sporting & match rifle

Bullet specification

0.3090 in / 7.849 mmBullet maximum

Factory examples

17 loadsSelected, sourced examples below

Weight in cited examples

150–200 grGrains measure mass, not powder charge

.300 WSM is identified by its complete cartridge designation. The resource-table alternative is 300 Winchester Short Magnum. A caliber number, bullet diameter, or family resemblance on its own does not identify ammunition compatibility.

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

The .300 Winchester Short Magnum was introduced in 2001, during the turn-of-the-century wave of new sporting cartridges. Winchester’s central goal was not simply to exceed its own .300 Winchester Magnum. It sought broadly comparable sporting performance from a short, wide, beltless case that could fit a .308-length action.

The cartridge therefore sold a different rifle package as much as a different velocity figure. A shorter action could support a compact hunting rifle, while the case geometry reflected contemporary interest in short, relatively broad cartridge designs. Magazine length also shaped its relationship with different bullet weights, illustrating that a compact action brings design tradeoffs as well as potential advantages. The .300 WSM became the best-known member of Winchester’s Short Magnum family. Its name links it commercially to the older .300 Win Mag, but its historical purpose was to offer a separate short-action approach to the same general hunting market.

Historical sources: Sierra: .300 WSM design background ↗ · Winchester: 2001 .300 WSM introduction ↗

Construction changes the story

Loads, variations & specialty offerings

In the cited .300 WSM examples, bullet weights are 150, 165, 180, 185, 200 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

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.

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

Keep exploring

Related references

Painted tips or polymer tips? Read the visual identification guide →

Browse the cartridge and gauge guides → · Return to the diameter comparison →

Trace the facts

Sources & methodology

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.

1. SAAMI: dimensional drawing · PDF p. 126 ↗
2. Sierra: .300 WSM cartridge background ↗
3. Federal · PDF pp. 58–59 ↗
4. Federal · PDF pp. 54–55 ↗
5. Hornady · PDF p. 187 ↗
6. Federal · PDF pp. 56–57 ↗
7. Winchester: 2001 .300 WSM introduction ↗

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.