Published: January 2026 | Last updated: May 2026
Disclaimer: Ballistic data in this article is drawn from Weatherby factory publications and established reloading references. All shooting and hunting distances should be determined by the individual shooter based on their equipment, skill level, and field conditions. Always confirm zero at the range before hunting season. For reloading data and cartridge history, see the 338 Weatherby RPM complete guide.
Weatherby introduced the 338 Weatherby RPM (Rebated Precision Magnum) in 2022 as part of a new family of beltless, rebated-rim cartridges designed for the Mark V’s distinctive 6-lug action. The RPM family was built to deliver magnum performance in a package that headspaces off the shoulder rather than a belt – an arrangement that improves concentricity, extends case life, and benefits handloading consistency compared to traditional belted Weatherby designs. By necking up the 6.5 RPM case to accept .338-inch bullets, Weatherby produced a cartridge that delivers performance comparable to – and in some respects surpassing – the 338 Winchester Magnum while fitting a more compact action envelope.
The 338 Weatherby RPM fires .338-inch diameter bullets in the 185 to 250-grain range, pushing 185-grain bullets to approximately 3,096 fps and 225-grain bullets to approximately 2,745 fps from a standard 26-inch barrel. These velocities match or slightly exceed the 338 Winchester Magnum, which typically generates 2,960 to 3,030 fps with comparable bullet weights. At these velocities, cup-and-core and thin-jacketed bullets can fragment excessively at close range – the same practical consideration that applies to all high-velocity Weatherby cartridges. Bonded and monolithic designs are strongly preferred for shots inside 150 yards on large game.
Like all Weatherby RPM cartridges, proprietary Weatherby brass and Weatherby’s 6-lug Mark V action are essentially required for this chambering. Factory ammunition is available from Weatherby directly. For context on where the 338 Weatherby RPM fits among .338 options, the 338 Winchester Magnum ballistics and 338 Lapua Magnum ballistics articles cover the full .338 tier. The 338 Weatherby RPM ballistics reference page also provides additional data.
Core External Ballistics
The three loads used throughout this article represent the practical hunting weight range for the 338 Weatherby RPM. Muzzle velocities reflect Weatherby factory data from a 26-inch barrel; shorter barrels lose approximately 25 to 40 fps per inch.
| Load | Bullet Weight | MV (fps) | BC (G7) | Muzzle Energy (ft-lbs) |
|---|---|---|---|---|
| Barnes TTSX / ELD-X | 185 gr | 3,096 | 0.295 | 3,947 |
| Nosler AccuBond / ELD-X | 225 gr | 2,745 | 0.332 | 3,765 |
| Federal Trophy Bonded / Partition | 250 gr | 2,563 | 0.310 | 3,650 |
All three loads launch above 3,650 ft-lbs – well above the elk energy threshold and into dangerous-game capable territory at close range. The 185-grain load starts fastest and carries the most energy inside 300 yards; the 225-grain load has the highest G7 BC at 0.332, which makes it the most efficient downrange performer at extended distance.
A note on the 185-grain load: while it starts with the highest muzzle energy of the three, its lower BC of 0.295 means it sheds energy faster than the 225-grain load at distance. By 700 yards the 225-grain has surpassed the 185-grain in retained energy. For shots inside 500 yards, the 185-grain is the flatter trajectory choice; for shots past 500 yards, the 225-grain is the stronger option.
Bullet Drop to 1,000 Yards (200-Yard Zero)
All data assumes a 200-yard zero, 59°F, sea level, and a 1.5-inch sight height.
| Range (Yards) | 185gr (in) | 225gr (in) | 250gr (in) |
|---|---|---|---|
| 100 | +1.6 | +1.8 | +2.0 |
| 200 | 0 | 0 | 0 |
| 300 | -7.5 | -8.8 | -10.0 |
| 400 | -21.5 | -25.5 | -28.5 |
| 500 | -43.5 | -52.0 | -58.0 |
| 600 | -75.5 | -90.0 | -100.5 |
| 700 | -120.0 | -142.5 | -158.5 |
| 800 | -180.0 | -213.0 | -237.5 |
| 900 | -256.5 | -304.0 | -339.5 |
| 1,000 | -350.5 | -415.0 | -463.5 |
With a 200-yard zero, the 338 Weatherby RPM’s trajectory holds within 2 inches of point of aim from the muzzle to approximately 255 yards with the 185-grain load – a genuine flat-shooting advantage over standard magnum cartridges at this bore diameter. At 300 yards, corrections range from 7.5 to 10 inches – manageable with a dialed elevation or a known holdover.
The 185-grain load is the flattest-shooting of the three at every distance, reflecting its higher starting velocity. At 500 yards it has dropped 43.5 inches versus 58 inches for the 250-grain – a 14.5-inch difference that represents meaningfully different elevation corrections in the field. For hunters who keep shots inside 500 yards, the 185-grain’s trajectory advantage is practically significant.
The 250-grain load’s arc-like trajectory past 400 yards reflects its lower starting velocity and lower BC relative to the 225-grain. At 500 yards it drops 6 inches more than the 225-grain, widening to 20 inches by 700 yards. For this cartridge, the 250-grain’s primary value is at close range inside 300 yards where its heavy mass and deep-penetrating construction provide the most reliable performance on the largest game – not at extended distance where its trajectory becomes demanding.
At 400 yards, all three loads require corrections of 21 to 29 inches. Precise range verification is non-negotiable at that distance and beyond.
Wind Drift (10 mph Full-Value Crosswind)
| Range (Yards) | 185gr (in) | 225gr (in) | 250gr (in) |
|---|---|---|---|
| 100 | 0.5 | 0.5 | 0.5 |
| 200 | 2.6 | 2.4 | 2.2 |
| 300 | 6.8 | 6.2 | 5.7 |
| 400 | 13.0 | 11.8 | 10.8 |
| 500 | 20.0 | 18.2 | 16.7 |
| 600 | 33.0 | 30.0 | 27.5 |
| 700 | 48.0 | 43.5 | 40.0 |
| 800 | 64.0 | 58.0 | 53.0 |
| 900 | 80.0 | 72.5 | 66.5 |
| 1,000 | 97.0 | 88.0 | 80.5 |
The 250-grain load shows the least wind drift at every distance – 80.5 inches at 1,000 yards versus 97 inches for the 185-grain, a 16.5-inch advantage driven by its combination of heavier mass and competitive BC. At 400 yards in a 10 mph crosswind, the 250-grain drifts 10.8 inches versus 13 inches for the 185-grain – a 2.2-inch difference that consumes a meaningful fraction of an elk’s vital zone margin.
At 500 yards, the 185-grain drifts 20 inches in a 10 mph crosswind – a full elk vital zone width. A hunter who misestimates a 10 mph wind by 2 mph at 500 yards will be off 4 inches, which is manageable; one who misestimates by 5 mph will miss the vital zone entirely. Wind estimation with a Kestrel or equivalent instrument is essential past 500 yards with any of the three loads.
Inside 400 yards in a 10 mph crosswind, the 250-grain drifts under 11 inches – within the margin of a center-mass hold on elk or moose with a known wind call. This is the practical shooting range where the 338 Weatherby RPM delivers its full capability without demanding extraordinary wind estimation skills.
Velocity Retention
The expansion thresholds: 1,800 fps for standard soft points; 1,600 fps for bonded designs like the AccuBond and ELD-X; 1,500 fps for monolithics like the Barnes TTSX.
| Range (Yards) | 185gr (fps) | 225gr (fps) | 250gr (fps) |
|---|---|---|---|
| 0 | 3,096 | 2,745 | 2,563 |
| 200 | 2,742 | 2,451 | 2,285 |
| 400 | 2,405 | 2,172 | 2,017 |
| 600 | 2,083 | 1,903 | 1,762 |
| 800 | 1,776 | 1,647 | 1,520 |
| 1,000 | ~1,490 | ~1,403 | ~1,291 |
The 185-grain load drops below 1,800 fps at approximately 810 yards; the 225-grain at approximately 655 yards; the 250-grain at approximately 590 yards. For practical hunting distances inside 600 yards, all three loads are above 1,800 fps and will expand reliably with any hunting bullet design.
The close-range velocity situation is the more important practical consideration. At 50 yards, the 185-grain load impacts at approximately 3,060 fps – velocities at which cup-and-core bullets can fragment aggressively, limiting penetration depth through heavy bone on elk and large bear. Bonded designs like the Nosler AccuBond and Hornady ELD-X, and monolithics like the Barnes TTSX, handle these close-range velocities safely.
Energy Retention
The thresholds: 1,000 ft-lbs for deer, 1,500 ft-lbs for elk and moose, 2,500 ft-lbs for dangerous game.
| Range (Yards) | 185gr (ft-lbs) | 225gr (ft-lbs) | 250gr (ft-lbs) |
|---|---|---|---|
| 0 | 3,947 | 3,765 | 3,650 |
| 100 | 3,098 | 2,990 | 2,898 |
| 200 | 3,095 | 2,989 | 2,894 |
| 300 | 2,375 | 2,284 | 2,220 |
| 400 | 1,826 | 1,796 | 1,800 |
| 500 | 1,393 | 1,402 | 1,449 |
| 600 | 1,044 | 1,074 | 1,148 |
| 700 | 776 | 814 | 903 |
| 800 | 564 | 609 | 714 |
| 900 | 409 | 450 | 565 |
| 1,000 | 293 | 326 | 447 |
For elk and moose, the 1,500 ft-lbs threshold is maintained as follows:
- 185gr load: approximately 540 yards
- 225gr load: approximately 505 yards
- 250gr load: approximately 510 yards
All three loads extend elk-class energy past 500 yards – a legitimate capability advantage over the 338 Winchester Magnum, which extends elk energy to approximately 490 to 530 yards with its best loads. The 185-grain load’s higher velocity gives it a slight edge in elk range over the heavier loads.
At 400 yards, all three loads deliver approximately 1,800 ft-lbs – a comfortable margin above the elk minimum for angled shots through heavy bone. The 338 Weatherby RPM genuinely excels at the 300 to 500-yard elk-hunting range, delivering more energy than standard .30 magnums at those distances while fitting a more compact action than the 338 Lapua Magnum.
For dangerous game – grizzly and brown bear – the 2,500 ft-lbs threshold is met by all three loads inside 350 yards. Inside 200 yards all loads deliver more than 2,800 ft-lbs – in the same performance bracket as the 338 Winchester Magnum at equivalent distances.
Terminal Performance Profiles
Barnes TTSX
The Barnes TTSX is an all-copper monolithic bullet expanding via four petals at velocities as low as 1,500 fps, retaining virtually 100 percent of its original weight. In gel at 338 Weatherby RPM impact velocities it drives 20 to 26 inches with a wide, consistent wound channel.
At the 338 RPM’s close-range velocities, the four copper petals open dramatically – the combination of .338-inch expanded diameter and complete weight retention produces exceptional tissue disruption. For the 185-grain TTSX, which starts at 3,096 fps, the close-range performance on bear and moose is exceptional. The TTSX is the optimal choice for lead-free hunting zones and for grizzly bear hunting inside 350 yards where complete structural integrity through heavy bone is mandatory.
A correction from the original article: it suggested the 185-grain TTSX for “predators and varmints.” A 185-grain .338-caliber monolithic bullet in a cartridge generating 3,947 ft-lbs of muzzle energy is not a varmint or predator load. It is a large-game and dangerous-game bullet. The TTSX belongs on elk, moose, and bear – not coyotes.
Best application: Grizzly, brown bear, moose, elk, and hogs at 50 to 500 yards. Required for lead-free zones.
Nosler AccuBond
The Nosler AccuBond bonds a lead core electrochemically to a tapered copper jacket, preventing core-jacket separation at the 338 Weatherby RPM’s extreme close-range impact velocities. A correction from the original article, which stated the AccuBond “often sheds weight on heavy bone”: the bonded construction specifically prevents core-jacket separation, and weight retention is consistently above 65 percent at any impact velocity this cartridge produces. In gel it expands to 1.5 to 1.8 times original diameter and penetrates 16 to 20 inches.
For the 338 Weatherby RPM, the 225-grain AccuBond is a capable all-around elk and moose load inside 500 yards, with the best long-range BC of the three loads at 0.332 and reliable expansion down to 1,600 fps. For open-country elk hunting where shots may extend to 500 yards, the AccuBond delivers the most consistent terminal performance across the full velocity range this cartridge generates.
Best application: Elk, moose, and deer at 75 to 500 yards.
Hornady ELD-X
The Hornady ELD-X uses a Heat Shield polymer tip maintaining consistent BC through flight and InterLock bonding preventing core-jacket separation. In gel it mushrooms to 1.6 to 1.8 times its original diameter and penetrates 16 to 22 inches with weight retention above 80 percent.
For the 338 Weatherby RPM, the ELD-X in 225-grain is arguably the best long-range hunting choice due to its high weight retention combined with a competitive BC. At close range, the bonded construction handles the RPM’s extreme velocities without fragmentation; at extended range, it expands reliably down to 1,600 fps. For hunters who want maximum versatility from close timber shots to 500-yard open-country shots on elk, the ELD-X covers both extremes dependably.
Best application: Elk, moose, and deer at 75 to 525 yards. Best all-around long-range hunting load.
Berger Elite Hunter
The Berger Elite Hunter uses a hybrid ogive combining tangent and secant nose geometry for high BC and seating consistency. On impact it penetrates 2 to 3 inches before the thin jacket initiates fragmentation, creating a large temporary cavity and broad permanent wound channel. In gel it penetrates 14 to 18 inches total with a wide fragmentation zone.
For the 338 Weatherby RPM, the Elite Hunter is the highest-BC option for long-range hunting work, where its aerodynamic efficiency extends velocity and energy retention better than standard hunting bullets of comparable weight. At 400 to 500 yards on elk and deer, its wound channel is decisive and its BC advantage over the Partition or Trophy Bonded is meaningful. Unlike the Berger Hybrid Target (which is a competition-only bullet), the Elite Hunter is specifically designed for hunting and performs predictably on medium to large game.
Best application: Elk and deer at 200 to 550 yards. Best choice when maximum BC and long-range energy retention are the priorities.
Federal Trophy Bonded
The Federal Trophy Bonded uses a bonded lead core locked inside a thick copper jacket, providing 90 to 95 percent weight retention and deep, straight-line penetration on the toughest game. In gel it expands to a broad, flat mushroom and penetrates 18 to 24 inches.
For the 338 Weatherby RPM, the 250-grain Trophy Bonded is the premier dangerous-game load for grizzly, brown bear, and bull moose inside 350 yards. Its combination of heavy mass (250 grains), near-complete weight retention, and bonded construction produces the deepest, most reliable penetration available in the lineup – ensuring vitals are reached from any angle, including frontal shots on charging bear. The lower BC makes it less efficient past 400 yards, but inside that distance it is the most capable penetration tool in the lineup.
Best application: Grizzly, brown bear, moose, and elk at 50 to 400 yards. Top choice for dangerous game at moderate range.
Practical Range Recommendations
The 338 Weatherby RPM delivers a genuine capability advantage over the 338 Winchester Magnum in a more compact, modern package – the beltless shoulder headspace, Weatherby Mark V 6-lug action, and slightly higher velocities combine to produce a capable, accurate hunting platform for the largest North American game.
Elk: All three loads meet the 1,500 ft-lbs elk standard past 500 yards – the 185-grain to approximately 540 yards, the 225 and 250-grain to approximately 505 to 510 yards. Inside 400 yards, all loads deliver approximately 1,800 ft-lbs with a comfortable margin above the elk minimum from any angle. For open-country elk hunting where shots may extend to 500 yards, the 225-grain AccuBond or ELD-X are the primary recommendations. For timber elk inside 300 yards, the Federal Trophy Bonded 250-grain provides the most reliable penetration on heavy bone.
Moose: Inside 450 yards with the AccuBond or ELD-X, or inside 350 yards with the Trophy Bonded. Moose require deep, reliable penetration through large muscle mass and heavy bone; the bonded and monolithic loads handle those demands reliably. At 400 yards the 250-grain Trophy Bonded retains approximately 1,800 ft-lbs – above the moose energy standard with useful margin.
Grizzly and brown bear: Inside 350 yards with the Federal Trophy Bonded 250-grain or Barnes TTSX 185-grain. Both loads deliver more than 2,500 ft-lbs at that distance with bullet construction that handles the most extreme bone impacts without failure. The 338 Weatherby RPM is a capable bear cartridge in a lightweight Mark V action that is practical to carry in the backcountry.
Deer: The 338 Weatherby RPM is substantially overpowered for deer. All three loads exceed the 1,000 ft-lbs deer minimum past 700 to 800 yards depending on load. For deer hunters who carry a Mark V chambered in the RPM as a primary platform, the 185-grain load minimizes meat damage while still producing decisive kills.
For a comparison of the 338 Weatherby RPM against the 338 Winchester Magnum and 338 Lapua Magnum in practical hunting terms, the big game caliber selection guide covers the full .338 tier.
FAQ
How does the 338 Weatherby RPM compare to the 338 Winchester Magnum?
The 338 Weatherby RPM generates approximately 100 to 150 fps more velocity than the 338 Winchester Magnum with comparable bullet weights, translating to roughly 200 to 300 ft-lbs more muzzle energy. Both extend the elk energy standard to approximately 500 to 540 yards with their best loads. The RPM’s beltless shoulder headspace improves concentricity and case life compared to the Winchester Magnum’s belted design. The 338 Win Mag has broader commercial ammunition availability and broader rifle platform support; the RPM is limited to Weatherby Mark V rifles. For hunters who prefer the Mark V platform, the RPM is the more modern and technically capable choice.
What is the maximum ethical elk range with the 338 Weatherby RPM?
All three loads meet the 1,500 ft-lbs elk standard past 500 yards – the 185-grain to approximately 540 yards, the 225 and 250-grain to approximately 505 to 510 yards. In realistic field conditions, 500 yards is a responsible practical maximum for most experienced hunters. Inside 400 yards, all loads deliver comfortable elk energy margins from any angle.
Why use bonded bullets at close range with the 338 Weatherby RPM?
The 185-grain load’s muzzle velocity of 3,096 fps produces impact velocities inside 100 yards that can cause cup-and-core bullets to fragment excessively, limiting penetration on large game. Bonded bullets like the AccuBond and ELD-X, and monolithics like the Barnes TTSX, maintain structural integrity at those velocities and produce reliable penetration regardless of range.
What is the barrel life of the 338 Weatherby RPM?
Like all overbore Weatherby cartridges, expect accuracy degradation between 1,500 and 2,000 rounds. The RPM’s beltless design may provide slightly better headspace consistency than older belted designs, but the fundamental overbore nature of the case produces similar throat erosion. Hunters shooting 75 to 150 rounds per year will see 10 to 25 years of barrel life – appropriate for a dedicated hunting rifle.
What powders work best for handloading the 338 Weatherby RPM?
The 338 RPM’s case capacity requires slow-burning powders. Hodgdon H4831SC and Hodgdon H4831 are the most commonly cited choices for 185 to 225-grain loads. Alliant Reloder 22 and Alliant Reloder 25 produce excellent velocities across the weight range. Hodgdon Retumbo and Alliant Reloder 26 suit the heavier 250-grain loads well. IMR 7828 SSC is another established choice. Use only Weatherby brass and always start 10 percent below published maximum charges. Published load data for the 338 RPM is less extensive than for the 338 Winchester Magnum given the cartridge’s recent introduction – cross-reference Weatherby’s own data with major manual sources.
What primers does the 338 Weatherby RPM use?
Large rifle magnum primers are standard. The Federal 215 and CCI 250 are most commonly specified. The Federal GM215M match magnum primer is preferred by precision handloaders for consistent ignition. The slow-burning powders filling the RPM’s large case demand the sustained ignition of a magnum primer.
Disclaimer: Ballistic data in this article is provided for reference purposes only. Actual performance will vary based on rifle barrel length, atmospheric conditions, altitude, and individual load parameters. Always verify your zero at the range before any hunt. Do not apply published handload data without consulting current reloading manuals from Weatherby or Hodgdon. Never exceed maximum published charges. The author and myreloading.com assume no responsibility for misuse of this information.
Editorial note: Originally published January 2026, revised May 2026. This revision converted all ballistic tables to a standard 200-yard zero, added a 100-yard row to the wind drift table, corrected the Nosler AccuBond description (the original stated it sheds weight on bone – bonded construction prevents this), corrected the characterization of the 185-grain TTSX as appropriate for “predators and varmints” (it is a large-game and dangerous-game bullet), added cup-and-core close-range fragmentation warning, added barrel life information, and added a velocity retention table.
