June 26, 2020
In the second half of the 20th century, Remington laid claim to the commercial 7mm rifle cartridge market with the .280 Remington in 1957 and the 7mm Remington Magnum in 1962. Both cartridges required full-length rifle actions.
Winchester saw an open door for short actions and entered the 7mm universe in 1963 with the compact .284 Winchester. It used a case with a rebated rim and a loaded length the same as the .308 Winchester.
The .284 Win. struggled with acceptance, but it hung on. However, things were afoot among silhouette competition shooters that would challenge that cartridge niche. Rifle metallic silhouette competition requires top accuracy, enough power to knock heavy steel targets off a rail 500 meters away, and mild recoil for sustaining long firing strings. Their focus was on conventional bolt-action rifles and the .308 Win. case necked down to handle .28-caliber bullets. Although there were several cartridge names applied to this wildcat, the 7mm-308 was the most common.
Fine competition performance does not always translate into a good game cartridge, but the 7mm metallic silhouette competition wildcat proved itself afield, too. Quick to standardize good wildcat cartridges, Remington introduced this cartridge as the 7mm-08 Remington in 1980.
As standardized, 7mm-08 case dimensions stay very close to the .308 Win. The shoulder origin distance and overall case length are slightly adjusted to maintain a case neck that is at least one bullet diameter in length. Maximum average pressure (MAP) under current piezo-electric standards is 61,000 psi. From a 24-inch test barrel, a velocity of 2,800 to 3,000 fps with bullets up to 145 grains is the norm.
Maybe silhouette shooters discovered something but didn’t know the reason why; at Speer we saw something in pressure barrel results. When shooting for reloading data development, we routinely recorded multiple shots at each of at least four charge-weight levels for each bullet-cartridge combination, then let the spreadsheet analyze how close to a straight line the entire set of data points fell.
A theoretically perfect “straight-line fit” is best case but can’t happen in the real world. If it did, it would have a value of 1.0. Most rifle cartridges posted high scores with some propellants or some bullet weights. The 7mm-08 scored exceptionally high for velocity and pressure consistency with all propellants we tested and with 140-, 150-, 160-, and 175-grain bullets. All loads scored over 0.95 and many scored over 0.99.
Does that kind of pressure consistency across the board with so many propellants and bullet weights translate to accuracy? Not necessarily, but if I were looking for a starting point to build a rifle for accuracy, then I would prefer to start with a cartridge that demonstrates such a strong pattern of consistency in the lab.
Published 7mm-08 Remington velocity data from ammo manufacturers and most reloading sources are from 24-inch test barrels, which, coincidentally, were the tubes common in silhouette competition. When hunters embraced the cartridge, they usually chose shorter barrels between 18.5 inches and 22 inches. Depending on the propellant, that drops velocity from the shortest factory rifles up to 150 fps slower than the pressure barrel.
What strikes me about the 7mm-08 is an intangible. It is one of the best “grow-into” hunting cartridges around. It was very popular around the CCI-Speer facilities for starting new shooters when I was there (1987–2007). Employees usually ordered the Remington Model 7 in 7mm-08. They removed and stored the factory walnut stock for later use and bought inexpensive synthetic stocks and shortened them to fit the trainee, be it child or spouse.
This system involved handloading, too, predictably a common practice among CCI-Speer employees. Range training started with loading 100- to 110-grain varmint bullets to velocities around 1,800 to 2,100 fps with Accurate 5744 or IMR SR4759. These loads produced very light recoil, and the small case helped maintain uniform pressures and velocities.
As the new shooter gained skill, confidence, and recoil tolerance, the teacher loaded 120- to 130-grain bullets in the 2,200 to 2,500 fps range. From there, the new shooter was ready for 140- to 150-grain bullets at start load velocities for most popular propellants. Before long, the trainee was using full-power loads.
What impresses me is how many of these trainees stuck with the same 7mm-08 rifle as adults (with the full-size stock reinstalled.). A friend’s son did exactly that. The 7mm-08 rifle he’d shot since his preteen years did all he needed. He proved this in his 20s by filling a cow elk tag with the animal quartering away from him. Shooting from about 150 yards, he put one Trophy Bonded Bear Claw 140-grain SP behind the ribcage on the left flank. The bullet broke the right shoulder and exited. We don’t know how far the bullet traveled after that, but the elk made it only two yards before going down.
The 7mm-08 isn’t the only cartridge that allows this load flexibility. However, it certainly makes it easy.