8 mm Remington Magnum

The 8 mm Remington Magnum belted rifle cartridge was introduced by Remington Arms Company in 1978 as a new chambering for the model 700 BDL rifle. The 8 mm Remington Magnum's parent case is the .375 H&H Magnum. It is a very long cartridge that cannot be used in standard length actions, such as those that accommodate the .30-06.

The cartridge produces up to 5694 J (4,200 ft • lbf) of muzzle energy when hand reloaded.

The 8 mm Remington Magnum was intended to compete with the .300 Weatherby Magnum and .338 Winchester Magnum. Remington’s decision to use a metric bullet may have been prompted by their past success with the 7 mm bore diameter.

Even though the 8 mm Remington Magnum has never been very popular, one would have to look long and hard before coming up with a better cartridge for use on elk, moose, and larger African antelope. On the other hand the .338 Winchester Magnum had a 30 year head start, is short enough for medium length actions, and is available with heavier bullets. Bullet selection is quite critical with the 8 mm Remington Magnum since the bullets have to be designed and constructed to hold together at magnum velocities.

Cartridge dimensions
The 8mm Remington Magnum has 6.43 ml (99 grain) H2O cartridge case capacity.



8mm Remington Magnum maximum C.I.P. cartridge dimensions. All sizes in millimetres (mm).

Americans would define the shoulder angle at alpha/2 = 25 degrees. The common rifling twist rate for this cartridge is 254 mm (1 in 10 in), 6 grooves, Ø lands = 8.00 mm, Ø grooves = 8.20 mm, land width = 3.10 mm and the primer type is large rifle magnum.

According to the official C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) guidelines the 8mm Remington Magnum case can handle up to 460 MPa (66717 psi) piezo pressure. This is a very high maximum chamber pressure limit for a rifle cartridge and ≈ 2.6 % above the SAAMI maximum piezo pressure rating of 448 MPa (65000 psi). In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers.

The German 8 x 68 S cartridge introduced in 1939 is probably the closest ballistic twin of the 8 mm Remington Magnum. The 8 x 68 S is however a rebated rim cartridge.

The 8mm Remington Magnum in field use
The 8mm Remington Magnum as a pure civil cartridge can be used in countries which ban civil use of former or current military ammunition.

A powerful cartridge like the 8mm Remington Magnum has its drawbacks. Like every other big game cartridge it presents a stout recoil. Since there are not many factory loads available, the 8mm Remington Magnum is often used by reloaders. They can use this cartridge to create powerful loads by handloading, whilst staying within the 448 MPa (65000 psi) SAAMI piezo pressure limit. Combined with bullets with jackets designed for magnum cartridge muzzle velocities and barrels of 650 mm (25.6 in) or longer to promote high muzzle velocities the 8 mm Remington Magnum offers the flattest trajectory and best long range performance of the commercially available 8mm rifle cartridges.

From 8mm caliber upwards the rise of sectional density and penetrating capability of practical spin stabilized rifle bullets (bullets up to 5 to 5.5 calibers in length) tends to flatten out. This means that 8mm cartridges that can generate magnum muzzle velocities can be utilized quite flexibly in hunting.

Loaded with light, short and soft nosed 8mm bullets the 8mm Remington Magnum can be used on remarkably small game. Loaded with heavy, long and hard (solid copper) bullets the 8mm Remington Magnum offers enough velocity derived power to penetrate heavy and dangerous game. The 8 mm Remington Magnum is suitable for hunting almost any game animal on the planet, though certain sub-Saharan Africa countries have a 9.53 mm (.375 in) or 10.2 mm (.40 in) minimum caliber rule for hunting Big Five game - i.e. leopard, lion, cape buffalo, rhino and African elephant. In the Central African Republic, where there are no ammunition limits for hunting Big Five game, the 8mm Remington Magnum’s somewhat smaller sister cartridge the 8 x 68 S is used successfully for hunting African elephant. At equal chamber pressure and 650 mm (25.6 in) barrel length the larger 8 mm Remington Magnum produces 3 to 5 % extra muzzle velocity.

8 mm cartridges compared
Maximum muzzle velocity comparison in % of the probably most proliferated European and American 8 mm rifle cartridges out of 650 mm (25.59 in) long barrels loaded with relatively light to heavy 8 mm bullets to their C.I.P. or SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute) sanctioned maximum pressures.

This comparison is not totally objective since the 8 mm Remington Magnum and .325 WSM operate at 448.16 MPa (65000 psi), the 8 x 68 S at 440 MPa (63817 psi), the 8 x 64 S at 405 MPa (58740 psi) and the 7.92 x 57 mm Mauser at 390 MPa (56564 psi) maximum chamber pressure. Higher chamber pressure results in higher muzzle velocities.

The 7mm STW
The 8mm Remington Magnum case has functioned as the parent case for the 7mm STW, which is essentially a 7mm (.284 caliber) necked-down version of the 8mm Remington Magnum. The wildcat status of the 7mm STW ended in 1996 when it got SAAMI certified and became an officially registered and sanctioned member of the 8mm Remington Magnum "family" of magnum rifle cartridges.

Wildcats
Cartridges that are not officially registered with nor sanctioned by C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) 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 caliber. A reason to change the original caliber can be to comply with a minimal permitted caliber 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 8mm Remington Magnum offers an exceptional sturdy, 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. With the 8 mm Remington Magnum as the parent case wildcatters have created 6.35mm (0.257 in) (.257 STW), 6.5mm (0.264 in) (6.5mm STW), .30 caliber (.30-8mm Remington Magnum, .300 Jarrett), 8mm caliber (8mm Jarrett), .338 caliber (.338 Jarrett), 0.358 in caliber (.358 STA) and 9.53mm (0.375 in) (.375 JRS) variants.

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