.257 Weatherby Magnum патроны туралы мәліметтер

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. Of the cartridges developed by Roy Weatherby, the .257 Weatherby Magnum was known to have been his favorite, and the cartridge currently ranks third in Weatherby cartridge sales, after the .30 378 Weatherby Magnum and the .300 Weatherby Magnum. The .257 Weatherby Magnum is capable of firing a Nosler Ballistic Tip bullet at generating 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 some 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).

The .257 Weatherby Magnum was designed in 1944 and introduced commercially in 1945 by Roy Weatherby as a wildcat cartridge as a chambering in his rifles. The 257 Weatherby Magnum is one of Roy Weatherby's favorite calibers. The original cartridge was developed using the H&H Super 30 (a close variant of the .300 H&H Magnum which in turn is based on the .375 H&H Magnum) shortened, blown out, and necked down to accept a .25 caliber (6.35 mm) bullet. Together with the .270 Weatherby Magnum, the 7mm Weatherby Magnum, and the .300 Weatherby Magnum, the .257 Weatherby Magnum were the earliest cartridges introduced by Roy Weatherby. The original cartridges were formed using Winchester's .300 H&H Magnum (H&H Super 30) and was only available as a component from Weatherby. Beginning in 1948 Weatherby began offering loaded ammunition for the .257 Weatherby Magnum cartridge which was loaded in house. Until then the cartridge was only available as a component brass which would require being loaded before use. Sometime later, the .257 Weatherby brass was manufactured by Richard Speer for Weatherby. However, due to space and organizational constraints Weatherby began looking for a source of ammunition for his cartridge. The search culminated in 1951 with Norma Projektilfabrik being awarded a contract to produce ammunition. Since then, all Weatherby Ammunition has been manufactured by Norma with the exception of a brief period of time between 1963 and 1964 when production moved to RWS/Dynamit Nobel, a company which had entered into partnership with Weatherby. Ever since the release of the .257 Weatherby Magnum it has remained one of the more popular cartridges in terms of Weatherby sales. Gun writers such as Layne Simpson consider the .257 Weatherby one of his favorite long range cartridges. The .30 Super Belted Rimless H&H manufactured by Winchester served as the direct parent cartridge for the case design. The .257 Weatherby Magnum was one of the first cartridges which used the shortened, blown out and necked down .375 H&H Magnum case and served as the forerunner to the standard length magnum cartridges such as the 7mm Remington Magnum and the .338 Winchester Magnum. There has been some speculation that Roy Weatherby may have used the full length .375 H&H Magnum case if he had slow burning powders available today when the cartridge was designed. The shortening of the case allowed for the more efficient use of the slow powder of the day, IMR 4350;

The .257 Weatherby Magnum is one of the most overbore cartridges available. The cartridge rates higher on the overbore index than the .264 Winchester Magnum and the 7mm Shooting Times Westerner but less than the 7mm RUM and the .30 378 Weatherby Magnum. The consequence of burning a large quantity of powder and driving a bullet faster is poor barrel life and throat erosion all of which affects accuracy and usable life of the firearm. Giving the barrel time to cool between each discharge of the weapon and following recommended cleaning procedures will help mitigate this issue and extend the usable life of the firearm chambered for this cartridge. Stainless steel barrels can further extend the barrel life of rifles chambered in the 257 Weatherby Magnum. Earlier .257 Weatherby Magnum rifles had a twist rate of 1 rotation in , which is too slow to stabilize long for caliber bullet. These bullets include most Barnes' bullets over and any conventional spitzer bullet of over Hornady's round nose bullet is made for such firearms which have the slower spin rate. Norma loads this bullet in the Weatherby's H257117RN ammunition for owner of such rifles who require a heavier bullet.