History
Shawn Carlock of Defensive Edge built the .338 Edge by opening the neck of the .300 Remington Ultra Magnum to take .338 inch bullets. The RUM is a big, beltless case descended from the .404 Jeffery, and necked up to .338 it drives the heavy 300 grain match bullets into .338 Lapua Magnum territory on brass that costs a fraction of the Lapua case.
There is no SAAMI or C.I.P. standard behind it, so the dimensions here are derived from the parent RUM and are approximate. That has not held it back: the Edge built a real following in extreme long range and long-range hunting, and for a handloader it remains one of the simplest routes into the 300 grain .338 class.
Lineage
Necked up, the case keeps the RUM's beltless head and roughly 30 degree shoulder and now takes a .338 inch (8.59mm) bullet. It feeds from a long or magnum action on a large rifle magnum primer. Among the big .338s built for extreme range it sits with the .338 Lapua Magnum, .338 Norma Magnum, .338-378 Weatherby, and the proprietary .338 EnABELR.
Specifications
| Spec | Value |
|---|---|
| Case type | Rimless rebated, beltless, bottlenecked (~30° shoulder) |
| Bullet diameter | 8.59 mm (.338 in) |
| Neck diameter | 9.47 mm (.373 in) |
| Shoulder diameter | 13.33 mm (.525 in) |
| Base diameter | 13.97 mm (.550 in) |
| Rim diameter | 13.56 mm (.534 in, rebated) |
| Case length | 72.39 mm (2.850 in) |
| Overall length | 91.44 mm (3.600 in) |
| Case capacity | ~105 gr H2O (nominal) |
| Primer size | Large rifle magnum |
| Belted | No |
| Rifling twist | 1 in 9 in (recommended, for 300 gr .338 match) |
| Max pressure | No SAAMI/C.I.P. standard; load to .300 RUM pressure |
| Recommended barrel | 36 in, 1:9 twist |
Dimensions are derived from the parent .300 RUM; the .338 Edge is a wildcat with no published standard, so treat the figures as approximate. The case is rebated, a .534 inch rim on a .550 inch body, which is how the fat RUM case still feeds through a standard magnum bolt face.
Barrel Design
The 1:9 twist is set for the 300 grain .338 match bullets the Edge is built around. Those long bullets carry the high ballistic coefficients that justify the recoil, and they need the fast twist to stay stable down through the transonic range at extreme distance. A slower twist cut for lighter hunting bullets would waste the case.
The Edge is a large overbore magnum, so it needs a long barrel to finish burning its powder charge. I'd put my baseline at 36 inches, which holds the heavy bullets supersonic past a mile, and the tables below are computed there. That is a deliberate extreme-range choice: the rifle is heavy and the muzzle blast serious. Barrel life is the other cost, since an overbore .338 erodes its throat, so treat the barrel as a consumable.
There is no factory .338 Edge ammunition, so these figures come from representative handloads. Confirm them against your own chronograph before trusting a dial.
Handload Performance
Handload · 300 gr Berger Hybrid OTM Tactical
| Range (yd) | Velocity (fps) | Elevation (mil) | Energy (ft-lb) | Windage (mil) |
|---|---|---|---|---|
| 0 | 2900 | -0.4 | 5602 | 0.3 |
| 100 | 2794 | 0.0 | 5201 | 0.1 |
| 200 | 2690 | -0.4 | 4821 | 0.3 |
| 300 | 2589 | -0.9 | 4464 | 0.4 |
| 400 | 2489 | -1.6 | 4127 | 0.6 |
| 500 | 2392 | -2.3 | 3811 | 0.7 |
| 600 | 2297 | -3.1 | 3514 | 0.9 |
| 700 | 2204 | -3.9 | 3235 | 1.1 |
| 800 | 2113 | -4.7 | 2975 | 1.2 |
| 900 | 2025 | -5.6 | 2731 | 1.4 |
| 1000 | 1939 | -6.6 | 2503 | 1.6 |
| 1100 | 1854 | -7.6 | 2289 | 1.8 |
| 1200 | 1771 | -8.7 | 2089 | 2.0 |
| 1300 | 1690 | -9.9 | 1901 | 2.3 |
| 1400 | 1610 | -11.2 | 1726 | 2.5 |
| 1500 | 1532 | -12.5 | 1563 | 2.8 |
| 1600 | 1455 | -13.9 | 1411 | 3.0 |
| 1700 | 1381 | -15.5 | 1270 | 3.3 |
| 1800 | 1308 | -17.1 | 1140 | 3.6 |
| 1900 | 1239 | -18.9 | 1022 | 3.9 |
| 2000 | 1172 | -20.8 | 914 | 4.3 |
| 2100 | 1113 | -22.9 | 826 | 4.7 |
| 2200 | 1077 | -25.2 | 773 | 5.0 |
| 2300 | 1052 | -27.6 | 737 | 5.4 |
| 2400 | 1030 | -30.2 | 707 | 5.8 |
| 2500 | 1010 | -33.0 | 680 | 6.2 |
| 2600 | 992 | -35.9 | 656 | 6.6 |
| 2700 | 975 | -39.0 | 633 | 6.9 |
| 2800 | 959 | -42.2 | 612 | 7.3 |
Muzzle velocity 2900 fps is the factory figure from a 36 in test barrel. 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 1:9 twist for the 300 grain .338 match bullets, and a long 36 inch barrel to collect the velocity and hold them supersonic past a mile. The Edge is an extreme-long-range cartridge; if you want something handier, a shorter barrel gives up the reach that is the whole reason to build one.
Is the .338 Edge a SAAMI cartridge?
No. The .338 Edge is a wildcat with no SAAMI or C.I.P. standard. You neck up factory .300 Remington Ultra Magnum brass to .338 and handload it; there is no factory .338 Edge ammunition. The dimensions on this page are derived from the parent .300 RUM and are approximate.
How does it compare to the .338 Lapua Magnum?
The two land in similar performance territory with 300 grain bullets. The .338 Edge gets there on inexpensive, common .300 RUM brass instead of the premium Lapua case, which is its main appeal to a handloader. The .338 Lapua is standardized and factory-supported, so it is the better choice if you want to buy ammunition off a shelf rather than build every round.
What is it good for?
Extreme long range and long-range hunting, where holding a heavy, high-BC .338 bullet supersonic past a mile is the point. It is not an all-around rifle cartridge; recoil, powder burn, weight, and barrel wear all make that clear. But for reaching out it is one of the most cost-effective ways into the 300 grain .338 class.