Pittsburgh, PA (Aug. 29, 2025) – Peterson Cartridge Co. of Pittsburgh, PA announces the addition of .257 Weatherby Magnum to its growing family of rifle casing calibers.

Originally developed by Roy Weatherby in 1944 and introduced in 1945, the .257 Weatherby Magnum was one of the original standard-length magnums developed by shortening the .375 H&H Magnum.  Extremely flat-shooting and known for long-range performance, the cartridge is historically a hunting cartridge ideal for whitetail, mule deer, and pronghorn when anticipating long shots in an open or western setting.  Remaining one of Weatherby’s best-sellers to this day, it is widely known that the .257 was Roy’s favorite cartridge.

“Roy Weatherby’s vision helped shape modern long-range hunting,” says Derek Peterson, president of Peterson Cartridge. “The enduring popularity of the .257 speaks for itself. Its proven performance and versatility make it a natural addition to our growing lineup of match-grade brass casings.”

The .257 is the eighth Weatherby caliber that Peterson Cartridge produces.
The others include:

• 6.5 Wby RPM
• 6.5-300 Wby Magnum
• .270 Wby Magnum
• 7mm Wby Magnum
• .300 Wby Magnum
• .338 Wby RPM
• .340 Wby Magnum

Peterson concludes, “We have our full lineup of Weatherby caliber casings in stock and ready to ship for hunting season.”