6.5×63mm Messner Magnum The 9.3×64mm Brenneke case functioned as the parent case for the 6.5×63mm Messner Magnum, which is essentially a 6.5 mm (.264 in) necked-down version of the 9.3×64mm Brenneke. The wildcat status of the 6.5×63mm Messner Magnum ended in 2002, when it was
C.I.P. certified and became an officially registered and sanctioned member of the German 64 mm "family" of magnum rifle cartridges. The 6.5×63mm Messner Magnum has 5.42 ml (83.5 grains) water cartridge case capacity.
6.5×63mm Messner Magnum maximum C.I.P. cartridge dimensions. All sizes in millimetres (mm). Americans would define the shoulder angle at alpha/2 = 29 degrees. The common
rifling twist rate for this cartridge is 200 mm (1 in 7.87 in), 6 grooves, Ø lands = 6.45 mm, Ø grooves = 6.70 mm, land width = 3.50 mm and the primer type is large rifle magnum. According to the official C.I.P. guidelines the 6.5×63mm Messner Magnum case can handle up to 440 MPa (64,000 psi) piezo pressure. The idea behind the 6.5×63mm Messner Magnum was to develop a very powerful 6.5 mm long range hunting cartridge that achieves very high muzzle velocities out of relatively short 600 mm (23.6 in) long rifle barrels. The developer, Joseph Messner from France, chose the 9.3×64mm Brenneke as parent case, since it offers enough case capacity and a competent gunsmith can relatively easy rechamber a standard Mauser 98 or any other bolt-action rifle to accept 9.3×64mm Brenneke based cartridges. Beside the 6.5×63mm Messner Magnum rimless rifle cartridge, Messner also designed a rimmed version for
break action rifles of the cartridge called the 6.5×63mmR Messner Magnum. Due to the large case capacity in relation to the 6.5 mm (.264 inch) calibre bore size the 6.5×63mm Messner Magnum is very harsh on barrels. It typically wears out a rifle barrel in 500 to 1000 rounds. A lot of thorough barrel cleaning (after every 5 shots) and carefully avoiding long strings of shots help to minimize barrel wear. This makes this cartridge impractical for most competition shooters who tend to fire a lot of rounds in practice to acquire and maintain expert long-range marksmanship. The German
6.5×68mm cartridge introduced in 1939 and the American
.264 Winchester Magnum cartridge introduced in 1959 are probably the closest ballistic twins of the 6.5×63mm Messner Magnum and both are more widely available to purchase at retail.
.376 Steyr Another commercial cartridge that uses the 9.3×64mm Brenneke as parent cartridge is the
.376 Steyr. This is essentially a shortened 9.3×64mm Brenneke cartridge necked-up to 9.5 mm (.375 in) calibre developed as an evolution of
Jeff Cooper's "Super Scout"
medium rifle concept, which was in turn an extension of his original
scout rifle concept. With a higher felt
recoil, the .376 Steyr is the largest practical cartridge for use in a short, lightweight weapon such as the
Steyr Scout rifle.
Wildcats Cartridges that are not officially registered with nor sanctioned by
C.I.P. (Commission Internationale Permanente Pour L'Epreuve Des Armes A Feu Portative) or its American equivalent, SAAMI (
Sporting Arms and Ammunition Manufacturers' Institute) are generally known as
wildcats. By blowing out standard factory cases, the wildcatter generally hopes to gain extra muzzle velocity by increasing the case capacity of the factory parent cartridge case by a few percent. Practically there can be some muzzle velocity gained by this method, but the measured results between parent cartridges and their 'improved' wildcat offspring is often marginal. Besides changing the shape and internal volume of the parent cartridge case, wildcatters also can change the original calibre. A reason to change the original calibre can be to comply with a minimal permitted calibre or bullet weight for the legal hunting of certain species of game. Wildcats are not governed by C.I.P. or SAAMI rules so wildcatters can capitalize the achievable high operating pressures. Because the 9.3×64mm Brenneke offers a pressure-resistant cartridge case that can relatively easily be reloaded with primers, powder and bullets and hence be reused several times, it has become quite popular amongst wildcatters. An example of a 9.3×64mm Brenneke-based wildcat is the
8mm Mázon. It was designed by Álvaro Mazón from Spain. This is essentially an 8 mm (.323 in) necked-down version of the 9.3×64mm Brenneke. A .338/8.5 mm caliber 9.3×64mm Brenneke-based wildcat example is the
8.5×64mm. The 8.5×64mm has 5.67
ml (87.5
grains) H2O cartridge case capacity. It was designed in 2001 by Lutz Möller from Germany to fire mono metal bullets also designed by Lutz Möller and other bullets. The chambering was designed to give excellent penetration
terminal ballistics as the
.333 Jeffery and various .338 magnums, while fitting standard
Mauser Gewehr 98 sized rifles with 9.3×64mm Brenneke sized magazine boxes. A .30 caliber 9.3×64mm Brenneke-based wildcat example is the
.30 Hembrook Long. It was designed in 2005 by Robert Hembrook of San Antonio, Texas. The finished case was designed to give similar ballistics to the various .300 magnums while having a usable length neck, and fitting standard
Mauser Gewehr 98 sized magazine boxes. ==See also==