History
Remington introduced the .300 Remington Ultra Magnum in 1999, the first of its beltless Ultra Magnum family and the largest-capacity .30 caliber that would still cycle through a standard-length action. The brief was velocity: outrun the .300 Winchester Magnum and the .300 Weatherby by a clear margin, and drive heavy .30 bullets faster than anything short of the .30-378.
It worked, and long-range hunters took to it. More than that, it set a template the cartridge world is still using, the big beltless shoulder-headspaced magnum. The .30 Nosler and .300 PRC have since refined that idea, both easier on barrels, but the RUM proved beltless .30 magnums could go this big.
Lineage
The case descends from the .404 Jeffery, its rim rebated to a .534 inch standard magnum bolt face so it drops into common actions, and it pushes a .308 inch (7.82mm) bullet. It is the parent of the 7mm and .338 RUM and the model the Nosler magnum family later copied. Its rivals are the .300 Win Mag, .30 Nosler, .300 PRC, and .30-378 Weatherby.
Specifications
| Spec | Value |
|---|---|
| Case type | Rimless (rebated), bottlenecked (beltless magnum) |
| Bullet diameter | 7.82 mm (.308 in) |
| Neck diameter | 8.74 mm (.344 in) |
| Shoulder diameter | 13.34 mm (.525 in) |
| Rim diameter | 13.97 mm (.550 in) |
| Case length | 72.39 mm (2.850 in) |
| Overall length | 91.44 mm (3.600 in) |
| Case capacity | ~110 gr H2O (nominal; varies by brand) |
| Primer size | Large rifle magnum |
| Belted | No |
| Rifling twist | 1 in 10 in (SAAMI reference); 1 in 9 in (recommended, for heavy match) |
| Max pressure | 65,000 psi (SAAMI) |
| Recommended barrel | 30 in, 1:9 twist |
Barrel Design
Few .30 calibers hold this much powder, so the RUM runs firmly overbore and lives or dies by barrel length. Cut it short and a great deal of velocity burns off as muzzle flash; run it long and that enormous charge becomes the speed the cartridge promises. For the long-range role this site is built around, I set the baseline at 30 inches, enough to capture the velocity without an unmanageable tube, with 26 inches about the shortest that still makes sense.
Twist should be 1:9 for the heavy 210 to 230 grain match bullets that justify a case this size. The 1:10 SAAMI reference is fine for 180 to 200 grain hunting bullets, but the long high-BC match bullets want the faster spin to stay stable downrange.
It is a barrel burner, no way around it. The charge erodes the throat quickly, so plan on rebarreling sooner than you would a .300 Win Mag. Length also brings tighter standard deviation on the match loads, which tells at distance. The tables below are computed at the 30 inch recommended barrel.
Range Ammo Performance
Remington Premier Long Range · 190 gr Speer Impact $2.92/rd
| Range (yd) | Velocity (fps) | Elevation (mil) | Energy (ft-lb) | Windage (mil) |
|---|---|---|---|---|
| 0 | 3210 | -0.3 | 4347 | 0.3 |
| 100 | 3054 | 0.0 | 3934 | 0.1 |
| 200 | 2901 | -0.3 | 3551 | 0.3 |
| 300 | 2752 | -0.7 | 3196 | 0.4 |
| 400 | 2608 | -1.3 | 2868 | 0.6 |
| 500 | 2467 | -1.9 | 2568 | 0.8 |
| 600 | 2331 | -2.6 | 2292 | 1.0 |
| 700 | 2199 | -3.4 | 2040 | 1.1 |
| 800 | 2072 | -4.2 | 1811 | 1.3 |
| 900 | 1949 | -5.1 | 1603 | 1.6 |
| 1000 | 1830 | -6.0 | 1412 | 1.8 |
| 1100 | 1714 | -7.1 | 1239 | 2.0 |
| 1200 | 1601 | -8.3 | 1081 | 2.3 |
| 1300 | 1491 | -9.6 | 938 | 2.6 |
| 1400 | 1385 | -11.0 | 809 | 2.9 |
| 1500 | 1283 | -12.5 | 695 | 3.2 |
| 1600 | 1187 | -14.3 | 594 | 3.6 |
| 1700 | 1105 | -16.2 | 515 | 4.0 |
| 1800 | 1061 | -18.4 | 475 | 4.4 |
| 1900 | 1029 | -20.8 | 447 | 4.8 |
| 2000 | 1001 | -23.5 | 423 | 5.2 |
| 2100 | 976 | -26.3 | 402 | 5.6 |
| 2200 | 952 | -29.4 | 383 | 6.0 |
| 2300 | 930 | -32.7 | 365 | 6.4 |
| 2400 | 909 | -36.1 | 348 | 6.8 |
| 2500 | 888 | -39.8 | 333 | 7.2 |
| 2600 | 868 | -43.7 | 318 | 7.6 |
| 2700 | 849 | -47.8 | 304 | 8.0 |
| 2800 | 831 | -52.1 | 291 | 8.4 |
| 2900 | 813 | -56.6 | 279 | 8.8 |
| 3000 | 796 | -61.3 | 267 | 9.2 |
| 3100 | 779 | -66.2 | 256 | 9.6 |
| 3200 | 763 | -71.4 | 246 | 10.0 |
| 3300 | 748 | -76.7 | 236 | 10.4 |
| 3400 | 733 | -82.3 | 227 | 10.8 |
Muzzle velocity 3210 fps is estimated at 30 in from the 26 in factory figure of 3130 fps at about 20 fps per inch. Expect your own barrel to read a little differently. Velocity is color coded green supersonic, yellow transonic, red subsonic; treat transonic and subsonic rows as approximate.
Match Ammo Performance
HSM Trophy Gold · 185 gr Berger VLD Hunting $3.90/rd
| Range (yd) | Velocity (fps) | Elevation (mil) | Energy (ft-lb) | Windage (mil) |
|---|---|---|---|---|
| 0 | 3318 | -0.2 | 4522 | 0.3 |
| 100 | 3153 | 0.0 | 4084 | 0.1 |
| 200 | 2992 | -0.2 | 3677 | 0.3 |
| 300 | 2835 | -0.7 | 3300 | 0.4 |
| 400 | 2681 | -1.2 | 2953 | 0.6 |
| 500 | 2533 | -1.8 | 2635 | 0.8 |
| 600 | 2389 | -2.4 | 2344 | 0.9 |
| 700 | 2250 | -3.1 | 2079 | 1.1 |
| 800 | 2116 | -3.9 | 1838 | 1.3 |
| 900 | 1986 | -4.8 | 1620 | 1.5 |
| 1000 | 1861 | -5.7 | 1422 | 1.8 |
| 1100 | 1739 | -6.7 | 1242 | 2.0 |
| 1200 | 1621 | -7.8 | 1079 | 2.3 |
| 1300 | 1506 | -9.1 | 931 | 2.6 |
| 1400 | 1395 | -10.4 | 799 | 2.9 |
| 1500 | 1289 | -12.0 | 682 | 3.2 |
| 1600 | 1188 | -13.7 | 579 | 3.6 |
| 1700 | 1103 | -15.6 | 500 | 4.0 |
| 1800 | 1058 | -17.7 | 460 | 4.4 |
| 1900 | 1026 | -20.1 | 432 | 4.9 |
| 2000 | 997 | -22.7 | 408 | 5.3 |
| 2100 | 971 | -25.6 | 387 | 5.7 |
| 2200 | 947 | -28.6 | 368 | 6.1 |
| 2300 | 924 | -31.9 | 350 | 6.5 |
| 2400 | 901 | -35.4 | 334 | 6.9 |
| 2500 | 880 | -39.1 | 318 | 7.3 |
| 2600 | 860 | -43.0 | 304 | 7.7 |
| 2700 | 840 | -47.1 | 290 | 8.1 |
| 2800 | 821 | -51.5 | 277 | 8.5 |
| 2900 | 803 | -56.0 | 265 | 8.9 |
| 3000 | 785 | -60.8 | 253 | 9.3 |
| 3100 | 768 | -65.8 | 243 | 9.7 |
| 3200 | 752 | -71.0 | 232 | 10.1 |
| 3300 | 736 | -76.4 | 223 | 10.5 |
| 3400 | 721 | -82.1 | 214 | 11.0 |
Muzzle velocity 3318 fps is estimated at 30 in from the 26 in factory figure of 3238 fps at about 20 fps per inch. Expect your own barrel to read a little differently. Velocity is color coded green supersonic, yellow transonic, red subsonic; treat transonic and subsonic rows as approximate.
Trajectory
FAQ
What barrel length and twist should I run?
A long barrel, 30 inches for the long-range role, because this large overbore case needs length to deliver its velocity. Pair it with a 1:9 twist to stabilize heavy 210 to 230 grain match bullets; the 1:10 reference twist is for lighter hunting bullets.
How hard is it on barrels?
Very. The .300 RUM burns one of the biggest .30 caliber charges in common use, which erodes throats faster than a .300 Win Mag or .300 PRC. High-volume and competitive shooters should budget for barrel replacement.
How does it compare to the .30 Nosler and .300 PRC?
All three are big beltless .30 magnums. The .300 RUM has the largest case and came first; the .30 Nosler fits the same performance into a slightly smaller package; the .300 PRC is the most efficient and has the deepest match-ammo support. The newer two are easier to live with.
What is the .300 RUM good for?
Long-range hunting where maximum .30 caliber velocity and energy matter and barrel life is an accepted cost. It is more cartridge than most shooting needs, and the people who want it know that going in.