.257 Weatherby Magnum
rifle cartridge
The .257 Weatherby Magnum is a .257 caliber (6.53 mm) belted bottlenecked cartridge. It is one of the original standard length magnums developed by shortening the .375 H&H Magnum case to approx. 2.5 in (64 mm). Of the cartridges developed by Roy Weatherby, the .257 Weatherby Magnum was his favorite. Today, the cartridge ranks third in Weatherby sales, after the .30-378 Weatherby Magnum and the .300 Weatherby Magnum.
The .257 Weatherby Magnum can fire a 115 gr (7.5 g) Nosler Ballistic Tip bullet at 3,400 ft/s (1,036 m/s) generating 2,952 ft⋅lbf (4,002 J) of energy which is comparable to factory loadings of the .30-06 Springfield and the .35 Whelen in terms of energy.
Discrepancies between the metric and U.S. diameters of the bullet may cause confusion. A .257 bullet has a metric bullet diameter of 6.53 mm. However, in Europe cartridge designation nomenclature for a large part relies on the bore diameter. As the bore diameter of the .257 Weatherby Magnum is .250 inches this would make it a 6.35 mm caliber cartridge which uses 6.5 mm bullets (not to be confused with 6.5 mm caliber cartridges which use 6.7 mm/.264" bullets).
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This entry incorporates text from “.257 Weatherby Magnum” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.