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In recent years, there has been a resurgence in popularity of .257-caliber cartridges, and the newest offering is the 25 Weatherby RPM, announced today. The .257 bore has been popular for more than a hundred years — its reputation established by cartridges such as the .250-3000 Savage, .257 Roberts, and the .25/06 Remington. Since the implementation of modern cartridge design, it fell into the shadows of the 6mm and 6.5mm and lacked a selection of modern, high-BC bullets — or the standardized twist rates to handle them. That has changed.
Cartridges like the 25 Creedmoor have re-invigorated the quarter-bore, inspiring a wider range of target and hunting bullets in heavier weights and more efficient profiles. These traditionally topped out at 120 grains, but now include projectiles weighing up to 138 grains. Despite starting at lower muzzle velocities than a traditional, say 110-grain .257 bullet, their low drag allows them to quickly overtake the lighter bullets in trajectory, wind drift, and impact velocity. The new 25 WBY RPM is built to handle these modern bullets, but also spit them out at blistering speeds. To some, that’s the best of both worlds.
25 Weatherby RPM Specs
- Parent Case: 6.5 WBY RPM
- Bullet Diameter: .257 inches
- Max OAL: 3.34 inches
- Shoulder: 35 degrees
- Case Length: 2.4 inches
- Bolt face: .477 inches
- Twist Rate: 1:7.5
- Velocity: 3000 to 3350 fps (24-inch barrel)
Weatherby Brings The Speed
The trademark of all Weatherby cartridges is velocity — and maximizing it. Like the 6.5 RPM, the 25 RPM brings the heat while embracing principles of modern cartridge design. It’s got a short enough head height to fit longer heavy-for-caliber bullets while maintaining an overall length that allows it to fit in a standard long action. Combine that with a steep shoulder, precise headspacing, and a modern chamber, and you’ve got a cartridge that should perform at distance.
In factory offerings from a 24-inch barrel, the 25 RPM should produce muzzle velocities of 3000 to 3350 fps using 133- to 107-grain bullets, respectively. The lightest loads will use the 107-grain Hammer HBC and 117-grain Hornady SST, while the heaviest will be the Berger 133-grain Elite Hunter. In trajectory, factory-loaded 133-grain Bergers should give a 4-inch advantage at 500 yards and 10 inches at 700 yards compared to factory 134-grain Hornady 25 Creedmoor ammunition.
Handloaders can beat velocities of cartridges like the .25/06 with similar bullets, and achieve better long-distance performance than even the .257 WBY while using more efficient projectiles. Like the 6.5 RPM, this cartridge is likely to prefer slow-burning magnum-class powders like Retumbo, H1000, StaBall HD, Magnum, or RL 26 — if you have any.
Looking Forward
We haven’t yet gotten a hold of any 25 WBY RPM ammo to test, but we look forward to thoroughly evaluating the promised potential and real-world performance of this new quarter-bore hot rod. More importantly, we’re curious how real results will stack up against other .25-caliber cartridges. Stay tuned.