The first cartridge in Weatherby's Rebated Precision Magnum (RPM) line was the 6.5 Weatherby RPM, introduced in 2019. Three years later, in 2022, Weatherby added another cartridge based on the same case, the 338 Weatherby RPM. Expanding this cartridge family, the company has recently introduced a new .257 caliber member - the 25 Weatherby RPM (257 WBY RPM), and SAAMI has just published the cartridge and chamber drawings for Weatherby’s new quarter bore. The third RPM is the 17th Weatherby cartridge.
SAAMI Specs Of The New 25 Weatherby RPM Cartridge
All Weatherby RPM cartridges have a rebated rim of .473" diameter with a .500” case body. These are basically the .284 Winchester case head and base dimensions. This case design allows using standard 30-06 Springfield/308 Winchester bolts but have a larger case capacity at a given case length. With an overall length of 3.34", the 25 Weatherby RPM is a standard/long action length cartridge that, according to Weatherby, provides magnum performance. The new 25 Weatherby RPM is designed with a focus on shooting heavier, high-BC bullets: the recommended twist rate is 1:7.5" and the case length of 2.4” results in ample room over the case (.94”) for those long ogive bullets. To download the full SAAMI cartridge and chamber drawings document for the 25 WBY RPM, click here.
According to the company, the 72.5 gr H₂O case capacity of the 25 WBY RPM is 40% more than that of the 25 Creedmoor. Here are a couple of graphs comparing the velocities and trajectories of the two cartridges.
The 25 WBY RPM ammunition will be initially available loaded with the following projectiles:
- Berger Elite Hunter 133gr (3,000 fps)
- Barnes LRX 117gr (3,150 fps)
- Hornady SST 117gr (3,150 fps)
- Hammer HBC Custom Bullet 107gr (3,350 fps)
The prices of the 25 WBY RPM ammo vary from $79 to $109 for a 20-round box, depending on the bullet choice. Unprimed 25 WBY RPM brass will also be available.
Weatherby currently offers the following models of Mark V and Model 307 rifles chambered in 25 Weatherby RPM:
- Mark V® Accumark ($2,149 – $2,199)
- Mark V® Apex® ($2,799 – $2,899)
- Mark V® Backcountry 2.0 ($2,649)
- Mark V® Backcountry 2.0 Ti ($3,499)
- Mark V® Deluxe ($2,999 – $3,199)
- Mark V® Backcountry Guide ($3,299)
- Mark V® Backcountry Guide Ti ($3,799)
- Mark V® Live Wild™ Carbon ($3,299)
- Mark V® Live Wild™ ($1,669)
- Mark V® Backcountry Capra ($3,499.00)
- Model 307™ Range™ XP 2.0 ($1,279)
- Model 307™ Range™ SF ($1,179)
- Model 307™ Adventure SD ($2,149)
- Model 307™ Alpine™ MDT ($3,249)
- Model 307™ Alpine™ MDT Carbon ($3,699)
- Model 307™ Alpine™ CT ($2,249)
- Model 307™ Alpine™ ST ($1,999)
- Model 307™ HUSH Edition ($1,349)
To learn more about the new 25 WBY RPM cartridge, listen to Episode 135 of Weatherby’s On Our Mark podcast.
Pictures by Weatherby and SAAMI
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