The 8mm Remington Magnum belted rifle cartridge was introduced by Remington Arms Company in 1978 as a new chambering for the model 700 BDL rifle. The 8mm Remington Magnum's parent case is the .375 H&H Magnum. It is a very long and powerful cartridge that cannot be used in standard length actions, such as those that accommodate the .30-06 Springfield.
Background
The 8mm 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 8mm Remington Magnum has never been very popular, it is a very suitable cartridge for the hunting of elk, moose, caribou, and larger African antelope. However, the .338 Winchester Magnum had a 30-year head start on the market, and is short enough for medium length actions, which increases the models of rifles it could be produced in. It is also available with heavier bullets, although this isn't a problem for people that load their own rounds of this caliber. Bullet selection is quite critical with the 8mm 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 piezo pressure. 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.
This means that 8mm Remington Magnum chambered arms in C.I.P. regulated countries are currently (2014) proof tested at PE piezo pressure.
The SAAMI Maximum Average Pressure (MAP) for this cartridge is piezo pressure.
The German 8×68mm S cartridge introduced in 1939 is probably the closest ballistic twin of the 8mm Remington Magnum. The 8×68mm 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, while 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 8mm Remington Magnum offers the flattest trajectory and best long range performance of the commercially available 8 mm rifle cartridges.
From 8 mm 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.