Hunting construction
Soft-point, bonded, partitioned, and monolithic expanding bullets are designed differently. Their intended impact-velocity ranges and use cases come from the bullet or ammunition manufacturer.
THE CARTRIDGE LIBRARY · SPORTING & MATCH RIFLE
.338 Remington Ultra Magnum
A beltless .338-caliber magnum in Remington's Ultra Magnum family. The RUM suffix identifies a specific case rather than a generic magnum load.
2A Ledger reference desk · Sources checked October 18, 2026
Read the dimensions
- Overall · min–max
- 3.450–3.600 in
87.630–91.440 mm - Case length · max
- 2.760 in
70.104 mm - Bullet maximum
- 0.3383 in
8.593 mm - Rim diameter · max
- 0.534 in
13.564 mm
Know the exact name
At a glance
- Cartridge family
- Sporting & match rifle
- Bullet specification
- 0.3383 in / 8.593 mmBullet maximum
- Factory examples
- 1 loadsSelected, sourced examples below
- Weight in cited examples
- 250 grGrains measure mass, not powder charge
.338 Remington Ultra Magnum is identified by its complete cartridge designation. The resource-table alternative is 338 Rem Ultra Mag. A caliber number, bullet diameter, or family resemblance on its own does not identify ammunition compatibility.
It is not .338 Winchester Magnum or .338 Lapua Magnum. Availability gaps in a selected catalog do not mean the cartridge is obsolete.
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 .338 Remington Ultra Magnum followed the .300 as the second member of Remington’s Ultra Magnum family. The program had begun with the .300 RUM in 1999 and represented a move toward large-capacity, beltless sporting magnums. Choosing a .338-caliber second offering emphasized the family’s role in substantial big-game rifles.
The .338 RUM sought performance above the established .338 Winchester Magnum and near the territory occupied by the .340 Weatherby. Its intended audience included hunters pursuing elk, large bears and heavier plains game, rather than owners looking for a modest general-purpose deer rifle. That positioning explains both the cartridge’s attraction and its specialist character. Its history belongs to the period when manufacturers were pursuing several different versions of the modern magnum: short-action cases at one end and very large-capacity, full-size sporting cases such as the Ultra Magnums at the other.
Historical sources: Sierra: .338 Remington Ultra Magnum cartridge history ↗
Construction changes the story
Loads, variations & specialty offerings
Match construction
Open-tip match and tipped match bullets prioritize consistency and aerodynamics. A match designation does not by itself mean the projectile was designed for hunting expansion.
Specialty offerings
Lead-free, reduced-recoil, and premium long-range products are separate load designs when offered. Compare the exact SKU, bullet weight, test barrel, and intended role rather than relying on a cartridge-wide average.
In the cited .338 Remington Ultra Magnum examples, bullet weights are 250 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
250 grains
2,860 fps
Core-Lokt pointed soft point
Compare all 1 cited factory load records
| Maker / product | Bullet mass | Published construction | Muzzle velocity | Test barrel | Source |
|---|---|---|---|---|---|
| RemingtonPR338UM2 / 27942 | 250 gr 16.20 g | Core-Lokt pointed soft point | 2,860 fps 872 m/s | Not stated here; see source | Remington · PDF p. 37 ↗ |
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
.338 Remington Ultra Magnum: factory velocity downrange
| Exact load | Source | Published points |
|---|---|---|
| 250 gr Remington Core-Lokt pointed soft point | Remington | 0: 2860; 100: 2647; 200: 2443; 300: 2249; 400: 2063; 500: 1887 |
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 .338 Remington Ultra Magnum?
A beltless .338-caliber magnum in Remington's Ultra Magnum family. The RUM suffix identifies a specific case rather than a generic magnum load.
What diameter does .338 Remington Ultra Magnum use?
The cited dimensional standard lists 0.3383 inches (8.593 mm), bullet maximum. This drawing convention is different from a casual caliber nickname.
Are similarly named cartridges interchangeable?
It is not .338 Winchester Magnum or .338 Lapua Magnum. Availability gaps in a selected catalog do not mean the cartridge is obsolete.
Are the graph values measured or estimated?
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.
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.
- SAAMI: dimensional drawing · PDF p. 139 ↗
- Sierra: .338 Remington Ultra Magnum cartridge background ↗
- Remington · PDF p. 37 ↗
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.