Rifle · SAAMI
.300 Remington Ultra Magnum
Remington's most powerful .30-caliber commercial cartridge.
- Caliber
- 0.308″ · 7.823 mm
- Introduced
- 1999
- Case
- Rebated
- Parent
- .404 Jeffery
- Primary use
- Hunting, Target
- Status
- Active
- Introduced
- 1999
- Type
- Rifle
- Origin
- United States
- Inventor
- Remington Arms
- Manufacturer
- Remington / Federal / Hornady
- Standard
- SAAMI
- Status
- Active
- Availability
- Specialty
- Case capacity
- 115 gr H₂O
- Twist (typical)
- 1:10
- Primer
- Large Rifle Magnum
- Case type
- Rebated
- Max pressure
- 65,000 psi
- Eff. range
- 600 yd
- Max range
- 1500 yd
- Recoil
- 28–40 ft·lb
Ballistics
Published velocity/energy data isn't available for .300 Remington Ultra Magnum. Parent case: 7mm Remington Magnum.
Performance
Dimensionscase measurements · scale drawing · size vs familiar rounds
Case dimensions — the scale drawing at the top of the page is built from these.
SAAMI · verified| Measure | mm | in | ✓ |
|---|---|---|---|
| Bullet ⌀ | 7.82 | 0.308 | ✓ |
| Neck ⌀ | 8.74 | 0.344 | ✓ |
| Shoulder ⌀ | 13.34 | 0.525 | ✓ |
| Shoulder angle | 30° | — | ✓ |
| Base ⌀ | 13.97 | 0.550 | ✓ |
| Rim ⌀ | 13.56 | 0.534 | ✓ |
| Belt ⌀ | n/a | ||
| Rim thickness | 1.27 | 0.050 | ~ |
| Neck length | 7.77 | 0.306 | ≈ |
| Case length | 72.39 | 2.850 | ✓ |
| Overall length | 91.44 | 3.600 | ✓ |
Size vs familiar rounds
Drawn at true 1:1 — every case is accurate relative to the others. Absolute size depends on your screen's pixel density, so measuring one against a real ruler may be off. .300 Remington Ultra Magnum is highlighted below.
Factory loads
Being verified
Advertised FPS, energy, and BC are withheld until loads clear verification.
Suitable powders
15 reloading powders listed for .300 Remington Ultra Magnum, fastest to slowest. Cross-reference in the finder →
Reloading costestimate cost per round vs factory
Estimate your cost per round and how it compares to factory. Inputs are yours — nothing is stored.
Cost estimate only — not load data. Charge weight is your input; follow published manuals for safe charges.
Firearms chambered in .300 Remington Ultra Magnum
12 models in the database chamber .300 Remington Ultra Magnum. Browse all →
Lineage
Connected reference
History
Remington introduced the Ultra Mag family in 1999–2000 on a large rebated-rim case that fit standard-length bolt faces. The .300 RUM pushed 180-grain bullets to 3,250 fps, delivering flat trajectories and long-range terminal energy for elk, moose, and large bears. The main limitation is barrel erosion: the high velocity and large powder charge accelerate throat wear significantly. Remington, Federal, and Hornady produce factory ammunition. The Model 700 in .300 RUM remains the primary platform.
FAQs
- What twist rate does .300 Remington Ultra Magnum use?
- .300 Remington Ultra Magnum typically uses a 1:10 twist rate.
- What bullet diameter is .300 Remington Ultra Magnum?
- .300 Remington Ultra Magnum uses a 0.308″ (7.823 mm) diameter bullet.
- Is .300 Remington Ultra Magnum still in production?
- .300 Remington Ultra Magnum is active; typical availability is specialty.
- What is .300 Remington Ultra Magnum used for?
- .300 Remington Ultra Magnum is primarily used for hunting, target.
- What is .300 Remington Ultra Magnum based on?
- .300 Remington Ultra Magnum is derived from the 7mm Remington Magnum case.
- What are the best powders for .300 Remington Ultra Magnum?
- Reloading powders commonly listed for .300 Remington Ultra Magnum include URP, N560, Norma MRP, Vihtavuori N160, among 15 suitable options.
Sources & provenance
- Standard SAAMI — SAAMI cartridge & chamber drawing — .300 Remington Ultra Magnum archived
- Standard SAAMI — ANSI/SAAMI Z299 — Cartridge & Chamber Drawings archived
- Standard SAAMI (Sporting Arms and Ammunition Manufacturers' Institute) — ANSI/SAAMI Z299.4 – 2015 (Centerfire Rifle) — Velocity & Pressure / Cartridge & Chamber Drawings · grain_ballistics, representative_gun archived
- Manufacturer Nosler — 300 RUM 180gr AccuBond Trophy Grade Ammunition · grain_ballistics, representative_gun archived
- Manufacturer Remington — Core-Lokt 300 Rem Ultra Mag Ammo, 180 Grain (index 27641) · grain_ballistics, representative_gun archived
- Manufacturer Nosler — 300 RUM 200gr AccuBond Trophy Grade Ammunition · grain_ballistics, representative_gun archived
- Manufacturer Nosler — 300 RUM 210gr AccuBond Long Range Trophy Grade Ammunition · grain_ballistics, representative_gun archived
- Manufacturer Hornady — 300 Remington Ultra Mag 220 gr ELD-X Precision Hunter (#8209) · grain_ballistics, representative_gun archived
- Secondary .300 Remington Ultra Magnum - Wikipedia · parent_cartridge
- Secondary .300 RUM - Remington's Ultra Magnum (Lynx Defense) · parent_cartridge
Data & sources. Specs compiled from the Lindcott Armory reference; availability counted from 23 live factory loads; the trajectory is modeled (point-mass), not measured. See methodology. Spotted an error? Report it →