Published: January 2026 | Last updated: April 2026
Disclaimer: All load data referenced in this article is drawn from published reloading manuals. The 300 RUM operates at 65,000 PSI with very large powder charges. Always begin 10% below published maximum charges and work up carefully. Large rifle magnum primers are required. Monitor barrel temperature during extended sessions – this cartridge generates significant heat per shot.
The 300 Remington Ultra Magnum was introduced by Remington in 1999 as the most powerful standard production .30-caliber cartridge available. Built on a rebated-rim case derived from the .404 Jeffery – the same parent case family as the Nosler cartridge line – the 300 RUM holds approximately 110 grains of water and drives 180-grain bullets at 3,300 FPS. That velocity is approximately 300-350 FPS faster than the 300 Winchester Magnum with the same bullet weight and represents the practical ceiling for .30-caliber performance in a standard long-action bolt gun.
The 300 RUM‘s design position is the .30-caliber equivalent of the 26 Nosler in the 6.5mm world: maximum velocity from a standard action, with the trade-offs that maximum velocity requires. Barrel life of 1,000-1,500 rounds, substantial recoil, large powder charges, and limited factory ammunition variety are the costs. For hunters who legitimately engage elk and moose at 600-900 yards in open Western or Alaskan country, the retained energy advantage at those distances is the benefit.
A Note on Case Design
The original article incorrectly describes the 300 RUM as a “belted magnum.” The 300 RUM uses a rebated-rim case derived from the .404 Jeffery. The rim is smaller than the case body (rebated), allowing the large-capacity case to feed from a standard .473-inch bolt face. There is no belt. This is the same architecture as the Nosler cartridge family and the 300 Norma Magnum. The rebated rim headspaces on the shoulder, providing more consistent headspace control than a belted design.
Technical Characteristics
| Characteristic | Value |
|---|---|
| Bullet Diameter | 0.308 inches |
| Case Length | 2.850 inches |
| Overall Cartridge Length | 3.600 inches (max) |
| Case Capacity | ~110 grains H2O |
| Case Type | Rebated rim, non-belted |
| Parent Case | .404 Jeffery family |
| Rim Diameter | 0.534 inches (rebated) |
| Max Avg Pressure (SAAMI) | 65,000 PSI |
| Typical Bullet Weight | 150-220 gr (practical: 180-210 gr) |
| Muzzle Velocity (180 gr) | ~3,250-3,300 FPS |
| Muzzle Velocity (200 gr) | ~3,100-3,150 FPS |
| Muzzle Velocity (220 gr) | ~2,950-3,000 FPS |
| Muzzle Energy (180 gr) | ~4,221 ft-lbs |
Who the 300 RUM Is For
The 300 RUM’s velocity premium over the 300 Winchester Magnum is real. At 1,000 yards, a 180-grain Nosler AccuBond Long Range at 3,300 FPS delivers approximately 1,400-1,500 ft-lbs. The 300 Winchester Magnum with the same bullet at 3,050 FPS delivers approximately 1,200-1,300 ft-lbs. The 300 RUM’s advantage at 1,000 yards is approximately 200-300 ft-lbs – meaningful for elk-sized game.
The 300 RUM makes practical sense if:
- You regularly take shots at 600-1,000 yards on elk, moose, or similar large game in open country
- Barrel life is secondary to maximum performance – you accept replacement every 1,000-1,500 rounds
- You hunt from a fixed setup (Alaska, open Western country) where the rifle stays in camp and weight is less critical
- You are pursuing dangerous game like large bears where maximum energy at any distance is the priority
The 300 RUM is likely not the right choice if:
- Most of your shots are inside 500 yards – the 300 Winchester Magnum or 300 WSM is adequate and more practical
- You do high-volume practice – the barrel life economics are punishing at volume
- You want broad factory ammunition availability when handloading is not possible
Recoil
At approximately 30-35 ft-lbs in a standard 9-pound hunting rifle, the 300 RUM is genuinely heavy-recoiling. A quality recoil pad is not optional equipment here – it is essential.
| Cartridge | Recoil (ft-lbs) | Rifle Weight (lbs) | Notes |
|---|---|---|---|
| 300 Winchester Magnum | 22-25 | 9.0 | Reference; manageable |
| 300 WSM | 23-25 | 8.25 | Similar to Win Mag; short action |
| 300 Norma Magnum | 26-30 | 10.0 | ELR precision platform |
| 300 RUM | 30-35 | 9.0 | Full ultra-magnum; recoil pad mandatory |
| 338 Lapua Magnum | 35-40 | 12.0 | Heavier; for very large game |
A muzzle brake drops the 300 RUM’s felt recoil to approximately 18-22 ft-lbs and makes the cartridge shootable for extended load development sessions. Most dedicated 300 RUM hunting and precision rifles include a muzzle brake.
Twist Rate
| Twist Rate | Optimal Bullet Weight | Barrel Length | Notes |
|---|---|---|---|
| 1:9 | 220-250 gr | 26-28 in | Best for heaviest long-range match bullets |
| 1:10 | 180-220 gr | 24-26 in | Standard; handles practical hunting range |
| 1:12 | 150-180 gr | 22-24 in | Lighter bullets; limits heavy match bullet use |
Most Remington 700 production rifles in 300 RUM use 1:10, which handles the standard 180-200 grain hunting bullet range. A 26-inch barrel is the standard for published data and produces maximum velocity from the very slow powders this case requires.
Ballistics and Field Performance
Trajectory
| Distance (yards) | Velocity (FPS) | Energy (ft-lbs) | Drop (inches) |
|---|---|---|---|
| Muzzle | 3,300 | 4,353 | -1.5 |
| 50 | 3,200 | 4,097 | +0.3 |
| 100 | 3,103 | 3,851 | +1.0 |
| 150 | 3,008 | 3,614 | +0.7 |
| 200 | 2,915 | 3,393 | 0.0 |
| 300 | 2,733 | 2,987 | -5.1 |
| 400 | 2,557 | 2,614 | -15.3 |
| 500 | 2,386 | 2,276 | -31.7 |
| 600 | 2,221 | 1,974 | -55.4 |
| 800 | 1,904 | 1,450 | -130.0 |
| 1,000 | 1,604 | 1,029 | -270.0 |
180-grain hunting bullet, BC 0.505, 3,300 FPS muzzle velocity. 59°F, sea level, 1.5-inch sight height, 200-yard zero.
At 1,000 yards the 300 RUM with a standard 180-grain hunting bullet delivers 1,029 ft-lbs at 1,604 FPS. With a higher-BC 200-grain bullet like the Nosler AccuBond Long Range, retained energy at 1,000 yards improves to approximately 1,200-1,400 ft-lbs.
Reloading the 300 RUM
Primers
Large rifle magnum primers are mandatory. The very large case volume with extremely slow powders requires the hottest available ignition.
| Primer | Type | Application |
|---|---|---|
| Federal 215 | Large Rifle Magnum | Top choice; hottest standard primer; essential for slow powders |
| Federal GM215M | Large Rifle Magnum Match | Precision loads; lowest standard deviation |
| CCI 250 | Large Rifle Magnum | Reliable; consistent; widely available |
| Remington 9-1/2M | Large Rifle Magnum | Natural Remington pairing; dependable |
| Winchester WLRM | Large Rifle Magnum | Consistent; works with very slow powders |
Cases
Remington and Norma are the primary brass sources. The rebated rim requires 300 RUM-specific shell holders.
| Brand | Notes |
|---|---|
| Remington | Factory equivalent; primary commercial source; adequate quality |
| Norma | Premium quality; excellent consistency; better case life |
| Nosler | Good quality; consistent |
The rebated-rim case requires a shell holder specifically for the 300 RUM. Standard .473-inch shell holders will not grip the case correctly at the rebated rim diameter (0.534 inches). Verify shell holder fit before beginning sizing operations.
Shoulder bump sizing: bump the shoulder 0.001-0.002 inches for consistent headspace. Full-length size for factory chambers. Trim to 2.840 inches after each firing. Anneal every 3-4 firings – the massive case at high pressure works brass hard and consistent neck tension is important for the consistent ignition this large case requires.
Bullets
The 300 RUM’s primary application is large, tough-bodied game at distance. Bullet selection should emphasize controlled expansion and deep penetration over maximum BC.
| Bullet | Weight | Type | Application | Notes |
|---|---|---|---|---|
| Nosler Ballistic Tip | 150 gr | BT | Deer; maximum velocity | Very high velocity; verify terminal integrity at close range |
| Sierra GameKing | 180 gr | SBT | Deer, elk; general hunting | Good BC; accurate; lightweight construction – use with caution at close range |
| Hornady ELD-X | 178 gr | Polymer Tip | Deer, elk; versatile | High BC; controlled expansion across velocity range |
| Nosler AccuBond | 180 gr | Bonded BT | Deer, elk; versatile | Bonded handles high close-range impact velocity |
| Nosler AccuBond Long Range | 200 gr | Bonded BT | Elk, moose; long-range | Best long-range hunting bullet; high BC + bonded |
| Hornady ELD-X | 200 gr | Polymer Tip | Elk at range | High BC; controlled expansion |
| Nosler Partition | 200 gr | Partition | Elk, moose, bear | Maximum penetration; controlled expansion at any velocity |
| Berger VLD Hunting | 210 gr | VLD | Long-range elk hunting | High BC; good terminal performance at reduced velocity |
| Barnes TTSX | 180 gr | Copper HP | Lead-free; tough game | Deep penetration; California legal |
| Berger Hybrid Target | 210 gr | HPBT Hybrid | ELR competition | Highest BC option for this case |
| Sierra MatchKing | 220 gr | HPBT | Long-range target | Outstanding accuracy; very high BC |
At 300 RUM velocities – 3,300 FPS with 180-grain bullets – lightly constructed hunting bullets frequently fail on close-range impacts before achieving adequate penetration depth. Use bonded construction (Nosler AccuBond, Hornady ELD-X) or partition design (Nosler Partition) for all elk and larger game hunting.
Powders
The 300 RUM’s 110-grain case capacity requires the very slowest available rifle powders. Faster powders like Hodgdon H4831SC are too fast for this case with hunting-weight bullets – they show position sensitivity and incomplete case fill.
| Powder | Bullet Weight | Start Charge | Max Charge | Approx Velocity | Notes |
|---|---|---|---|---|---|
| Hodgdon Retumbo | 180-200 gr | 92.0 gr | 102.0 gr | ~3,320 FPS | Top choice; consistent; excellent case fill; widely available |
| Hodgdon Retumbo | 200-220 gr | 89.0 gr | 99.0 gr | ~3,140 FPS | Best with heavier hunting bullets |
| Hodgdon H1000 | 180-200 gr | 91.0 gr | 101.0 gr | ~3,280 FPS | Good consistency; good velocity |
| Hodgdon H1000 | 200-220 gr | 88.0 gr | 98.0 gr | ~3,110 FPS | Works with heavier hunting bullets |
| Alliant Reloder 33 | 200-220 gr | 91.0 gr | 101.0 gr | ~3,120 FPS | Temperature stable; good for varied-climate hunting |
| Alliant Reloder 26 | 180-200 gr | 90.0 gr | 100.0 gr | ~3,260 FPS | Temperature stable; high velocity with lighter bullets |
| Vihtavuori N570 | 210-220 gr | 91.0 gr | 101.0 gr | ~3,040 FPS | Premium consistency; heaviest bullets |
| Vihtavuori N568 | 200-220 gr | 91.0 gr | 101.0 gr | ~3,080 FPS | Good consistency; competition-grade loads |
| Accurate MagPro | 180-200 gr | 89.0 gr | 99.0 gr | ~3,220 FPS | Ball powder; good metering; consistent |
| IMR 7977 Enduron | 180-200 gr | 90.0 gr | 100.0 gr | ~3,230 FPS | Temperature stable Enduron; reduced copper fouling |
| Norma MRP | 180-200 gr | 89.0 gr | 99.0 gr | ~3,210 FPS | Good consistency; natural pairing with Norma brass |
| Hodgdon US 869 | 200-220 gr | 92.0 gr | 102.0 gr | ~3,060 FPS | Ball powder; metering advantage; slow enough for heavy bullets |
All charge weights are reference figures. Verify against current published Remington, Hodgdon, Alliant, or Norma data before loading. These are very large charges – begin 10% below listed maximums. Work up in 0.5-grain increments. Monitor barrel temperature carefully.
Hodgdon Retumbo is the primary powder for the 300 RUM and has the most published data associated with this cartridge. Its very slow burn rate fills the case completely at appropriate charge weights, minimizes position sensitivity, and produces excellent velocity and consistency. Most Remington factory 300 RUM data was developed with Retumbo.
Alliant Reloder 33 is the temperature-stable competition alternative for hunters who develop loads in one climate and use them in another. Its performance consistency across temperature extremes is better than Retumbo and H1000 in most published reports.
Practical Hunting Applications
Elk at Long Range
The 300 RUM’s primary argument for existence is elk at 700-1,000 yards in open country – Alaskan tundra, high-altitude Western meadows, or any setting where shots beyond 600 yards occur routinely. At 700 yards with a 180-grain Nosler AccuBond at 3,300 FPS muzzle velocity, the 300 RUM is delivering approximately 1,700-1,800 ft-lbs – well above the threshold for elk. At 900 yards it remains above 1,300 ft-lbs. Compare this to the 300 Winchester Magnum at the same distance: approximately 1,400-1,500 ft-lbs at 700 yards. The 300 RUM carries roughly 300 ft-lbs more energy at 700 yards. For hunters who legitimately take these shots in appropriate conditions, that margin is real.
Use the Nosler AccuBond Long Range 200-grain or Nosler Partition 200-grain for elk. Both are designed to perform reliably from close-range 3,000+ FPS impact to long-range 2,200 FPS impact. Standard cup-and-core hunting bullets will fail on close-range impacts at 300 RUM velocities.
Moose and Large Bears
With a Nosler Partition 200-grain or Barnes TTSX 180-grain, the 300 RUM is among the most capable standard-production .30-caliber cartridges for moose and large bears. The high velocity and heavy bullet weight combination provides the energy and penetration that North America’s largest game animals demand.
Barrel Life
The 300 RUM’s barrel life is the cartridge’s most significant practical constraint for high-volume shooters. At 1,000-1,500 rounds before accuracy degradation in typical loads, a hunter who fires 100-150 rounds per year will get 7-10 years from a barrel. A competitor or high-volume practice shooter may go through a barrel in a single season.
The economics are real: a quality installed barrel for a Remington 700 costs $400-700. At 1,200-round barrel life, that is $0.33-0.58 per round in barrel cost alone. For dedicated hunting use where volume is limited, this is acceptable. For practice-intensive shooting, it is not.
Conclusion
The 300 Remington Ultra Magnum is the maximum-performance .30-caliber hunting cartridge – the one that produces the most energy, the flattest trajectory, and the most retained velocity at distance of any standard long-action .30-caliber production cartridge. For hunters who legitimately use that performance, it is an appropriate and effective tool.
The trade-offs are substantial and honestly stated: short barrel life, large powder charges, significant recoil, limited factory ammunition, and case headspace on a rebated-rim design that requires attention. For hunters who do not need the velocity ceiling that the 300 RUM provides – and most hunters do not – the 300 Winchester Magnum or 300 WSM provide 90-95% of the performance with substantially better practical characteristics.
For related reading, see 300 RUM ballistics, 300 Winchester Magnum complete guide, 300 PRC complete guide, and 26 Nosler complete guide for comparison with ultra-magnum design philosophy.
Disclaimer: All load data in this article is for reference purposes only. Verify all charges against current published reloading manuals before loading. Large rifle magnum primers are required. Never exceed published maximum charges. Always begin 10% below listed maximums and work up while monitoring for pressure signs. Monitor barrel temperature during extended sessions.
Editorial note: This article was originally published in January 2026 and revised in April 2026. The revision corrected the original article’s description of the 300 RUM as a “belted magnum” – it is a rebated-rim non-belted case – and explained the practical implications for headspacing and reloading technique. Added a “who is this for” decision framework, corrected the ballistics table to 200-yard zero per site standard with data to 1,000 yards, a complete powder table with 12 powders and charge weight ranges, expanded bullet selection with 11 bullets including explicit warning on lightly constructed bullets at ultra-magnum velocity, barrel life economics with per-round cost analysis, recoil table, and honest positioning against 300 Winchester Magnum and 300 WSM for hunters who do not need the velocity ceiling.
