The 7mm Remington Magnum rifle cartridge was introduced as a commercially available round in 1962, along with the new Remington Model 700 bolt-action rifle. It is a member of the belted magnum family that is directly derived from the venerable .375 H&H Magnum. The original purpose of the belted magnum concept taken from the .300 H&H Magnum and .375 H&H Magnum, was to provide precise headspace control, since the sloping shoulders, while easing cartridge extraction, were unsuitable for this purpose. Improved cartridge extraction reliability is desirable while hunting dangerous game, in particular when a fast follow-up shot is required. The 7mm Remington Magnum is based on the commercial .264 Winchester Magnum, .338 Winchester Magnum, and .458 Winchester Magnum, which were based on the same belted .300 H&H Magnum and .375 H&H Magnum cases, trimmed to nearly the same length as the .270 Weatherby Magnum.
History
On its introduction, the 7mm Remington Magnum substantially usurped the market share held by the .264 Winchester Magnum, which went into sharp decline in popularity and sales after 1962. By 1963 Winchester introduced the .300 Winchester Magnum to compete with Remington's new belted magnum cartridge. Both cartridges have remained the most popular magnum calibers among hunters and shooters ever since.
Les Bowman, hunting editor and outfitter was much responsible for the development and introduction of the cartridge, as he noticed the need for a flatter-trajectory cartridge capable of taking elk-sized game to considerable ranges where he took his clients as the .300 Weatherby Magnum produced too much recoil for many hunters, resulting in poor shot placement, and the .270 Winchester, with the bullets available back in the day, weren't always as effective at longer distances and did not carry enough downrange energy. Thus, he found in the .275 Holland & Holland Magnum, a suitable alternative, but unavailable in the US.
Design
The 7mm Remington Magnum offers ballistics better than the .30-06 Springfield with all available bullet weights, one of the more popular loads being a 160-grain spitzer loaded to . This is due both to the higher muzzle velocity of the magnum compared to the Springfield and that .284 diameter bullets tend to have better ballistic coefficients than .308 diameter bullets of comparable mass. Because of the smaller bullet diameter .284 diameter also have higher sectional density than .308 diameter bullets, and because of that better penetration in the target (it takes a 206-grain .308 diameter bullet to get the same sectional density as a 175-grain .284 bullet, an increased weight that requires 15-20% more muzzle energy to get the same muzzle velocity). The heaviest commercially loaded ammo available for the 7mm is 195 grains, while the .30-06 Springfield can be loaded with bullets up to 220 grains, but for a .308 caliber to equal the flat trajectory and penetration of a .284 diameter 180-grain bullet with a muzzle velocity of 2,860 ft/sec (870 m/s), as offered for the 7mm Remington Magnum, requires muzzle energy close to what the .300 Winchester Magnum can offer, i.e. well beyond what the .30-06 can deliver.
Cartridge dimensions
The 7mm Remington Magnum has 5.31 ml (82-grain) H2O cartridge case capacity.
7mm Remington Magnum maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).
Americans would define the shoulder angle at alpha/2 = 25 degrees. The common rifling twist rate for this cartridge is 241 mm (1 in 9.49 in), 6 grooves, Ø lands = 7.04 mm, Ø grooves = 7.21 mm, land width = 2.79 mm. The cartridge uses a large rifle magnum primer type.
According to the official C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) rulings, the 7mm Remington Magnum case can handle up to Pmax 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 as of 2016, 7mm Remington Magnum chambered arms in C.I.P. regulated countries are proof tested at PE piezo pressure.
The SAAMI maximum average pressure (MAP) for this cartridge is piezo pressure.