7mm-08

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If you are a fan of range days, the 7mm will offer a whole world of pleasure and comfort round after round.

I have always thought that the .308 Win case is proportionally perfect to look at. The dimensions are pleasing to the eye, and the performance and popularity of the round speaks for itself. So it is little wonder that this case was necked down to 7mm to take advantage of the array of superb projectiles available in this bullet diameter. Remington introduced the 7mm-08 in the 1980s, but it could hardly lay claim to ownership as the 7mm-08 wildcat had been in use since before 1958. There is nothing fancy about the commercial offering either – it is simply the original .308 Win case necked down to take a 7mm bullet.

Although Remington claimed the 7mm-08 “was the first 7mm round designed for use in short actions” (Frank C Barnes, Cartridges of the World), this overlooked the fact that the .284 Winchester had been on the go since 1963. I will include no more mention of the .284 here, as it will be suitably discussed next month. It has prompted me to plan a custom rifle in the calibre, so it is not to be missed.

Today, most manufacturers offer a handful of models in 7mm-08. It was quickly taken up by silhouette shooters keen to take advantage of the superior ballistics over the .308 Win. The 7mm-08 exhibited a flatter trajectory and less wind drift, while benefiting from the .308 Win’s inherent accuracy and long barrel life.

The table below shows the performance of the two calibres, taking a 168-grain Berger VLD (BC=0.486) 7mm-08 and comparing it to a 170-grain Sierra MK (BC=0.496) from the .308. For long-range delivery of bullets greater than 150-grain, the 7mm-08’s advantages are pretty clear. The difference in retained energy at 1,000 yards is surprising, with 7mm-08 delivering over 150ft/lb more than the historically chosen long-distance calibre. Combined with the reduced drop and wind drift evident in the table, it is obvious to see why shooters partaking in precise long-distance silhouette shooting were quick to trade in their outclassed .308 Winchesters.

It is true, however, that the .308 is capable of pushing much heavier bullets at faster velocities than the 7mm-08, bringing the ballistic coefficients back in line. The trade-off here is recoil – most people would not want to shoot many rounds of the 210-grain projectile required to match the ballistics of a 175-grain 7mm. This would equate to something like 17 per cent more recoil if the bullet is pushed at the 2,800fps required to equal trajectory and wind drift (percentage and figures produced by Bryan Litz, Applied Ballistics). I hasten to add that this would not be a safe load in most instances, and is merely to illustrate the point.

Obviously recoil isn’t of great consideration to hunters, with most rarely firing more than two shots in an outing. If you are a fan of range days, however, the 7mm will offer a whole world of pleasure and comfort round after round.

But what of the other 7mm rounds? We could not talk about the 7mm-08 without mentioning the 7×57 Mauser. The two produce similar ballistics to one another with the lower- to middle- weight bullets, although the slightly larger case capacity of the old 7×57 makes it more versatile than the relatively new kid on the block. Once we get to 170-grain and above, bullets have to be seated quite deep in the 7mm-08, further reducing case capacity. The 7mm-08 doesn’t have the grunt required to shoot those heavier bullets to the same standard as the 7×57, with MVs 100-180fps less. Having said that, up to 160 grains the two calibres are pretty much on par, although the more efficient case of the 7mm-08 makes for tighter long-range groups.

The 7mm bullet is without a doubt my favourite all-round calibre. Choosing the case to send that fantastic projectile down-range is where it becomes a matter for serious contention. For me, the short action and accuracy benefits over the 7×57 don’t quite make up for the reduced performance in the heaviest bullet weights. However, that may be because my rifle sees extensive use in Africa as well as the UK. Does it mean that the reign of the .308 Winchester should now be over? Probably not, but if factory rifle and ammo production were equal, and they had been launched around the same time, I would bet that most hunters would have reached for smaller 7mm-08 off the rack in the gun shop.  BP 

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