The .308 Winchester (7.62mm NATO)
By Chuck Hawks
The .308 Winchester came about as a result of the U.S. Army's search for a cartridge to replace the venerable .30-06 Springfield. There was nothing wrong with the ballistics of the .30-06, in fact they were considered ideal, but the cartridge itself was too long for optimum operation in automatic weapons. In fact, the .30-06 was the longest service cartridge in the world.
The Army started experimenting with the .300 Savage, and ended up with what they called the T-65 experimental round. Winchester brought out the civilian version of the new cartridge as the .308 Winchester in 1952. This was adopted in 1954 by the U.S. and NATO as the 7.62mm NATO. It was chambered in various service rifles (including the U.S. M-14), sniper rifles, and machine guns. It is still service standard for the latter two applications today. The new 7.62mm NATO round exactly duplicated the ballistics of the .30-06 standard M2 ball ammunition: a 150 grain FMJ spitzer bullet at 2,750 fps. In overall cartridge length the .308 is .55 inch shorter and about 10% lighter than the earlier .30-06 cartridge.
The .308 has a 2.81" maximum cartridge overall length. The case is 2.015" long, rimless, with a standard .473" rim diameter, a 20 degree shoulder, and slight body taper. It uses standard .308" diameter bullets. The SAAMI mean maximum pressure for the .308 is 52,000 cup.
The .308 Winchester has turned out to be a great sporting cartridge, both for hunting and competitive target shooting. It perfectly fills the need for a high performance, all-around short action cartridge for the hunter. And it has proven to be perhaps the most accurate high intensity .30 caliber cartridge ever developed. It is used in match target competition all the way out to 1,000 yards. Today the .308 Winchester is the fifth best selling centerfire rifle cartridge in America, and it is used for big game hunting on every continent. Ammunition is manufactured in North America, Europe, Africa, Australia, and beyond, and can be purchased wherever big game is hunted.
There is a very large selection of factory loads for the caliber, particularly in the most useful range of 150-180 grains. The reloader has bullet choices ranging from 100 grain to 200 grain. With the right loads a hunter armed with a .308 can tackle everything from jackrabbits to elk, and it shoots flat enough to make fairly long range shots possible. Thick-skinned and dangerous game should be left to the medium and big bores, but nearly everything else is within the capabilities of the .308 Win.
The fact that the .308 Winchester is chambered in so many neat short action rifles is one of its greatest attractions. These include light weight, short, bolt action rifles like the Browning Micro Medallion, Remington Model 7 series, Ruger M-77RL Ultra Light and M-77RSI International, Savage Model 11 series, Weatherby Ultra Lightweight, and Winchester Model 70 Featherweight. There are lever action rifles like the Browning BLR and Lightning BLR, and the classic Savage Model 99 (unfortunately discontinued). There are a number of semiautomatic rifles chambered for the .308, plus the Remington 760 pump action. Almost every standard weight bolt action rifle in the world is also chambered for the cartridge. Along with its popular offspring the .243 Winchester, the .308 has probably been offered in more rifle models than any other cartridge in the world.
Recoil energy is about 17.5 ft. lbs. in an 8 pound rifle shooting the 180 grain factory load. In an ultra-light 6.5 pound mountain rifle it would be about 22 ft. lbs.
For all of the above reasons, the .308 Win. is regarded by most experts as one of the few true all-around cartridges for the one rifle hunter, and it is on my short list of all-around cartridges as well. It is the choice for the person who chooses a short action rifle for all-around service.
The common factory loaded bullet weights for the .308 are 150 grain, 165 grain, and 180 grain. These are the best bullet weights for almost all medium and big game hunting with the .308, so they are also the bullets most used by reloaders.
The Sierra 150 grain boat tail spitzer has a ballistic coefficient (BC) of .416 and a sectional density (SD) of .226. This is the bullet I use most in my .308. According to the second edition of the Sierra Bullets Reloading Manual 42.6 grains of W748 powder gives this bullet a MV of 2500 fps, and 49.9 grains gives a MV of 2900 fps.
The Sierra 165 grain boat tail spitzer has a BC of .453 and a SD of .248. Sierra figures call for 41.4 grains of W748 powder for a MV of 2400 fps, and 47.2 grains of W748 for a MV of 2700 fps.
The Sierra 180 grain boat tail spitzer has a BC of .530 and a SD of .271. The Sierra Bullets Reloading Manual shows that 39.9 grains of W748 powder gives a MV of 2300 fps, and 45.5 grains of W748 gives a MV of 2600 fps.
Bullets as heavy as 200 grains can be used successfully in the .308 Win. The Speer Reloading Manual No. 13 shows the top 4 handloads for the 200 grain spitzer at just over 2,400 fps. That bullet has a BC of .556 and a SD of .301.
Because of the diversity of loads and bullet styles, it is hard to generalize, but the following are typical American factory loads and are also probably representative of the majority of handoads. The 150 grain spitzer bullet is usually loaded to a muzzle velocity (MV) of 2,820 fps and muzzle energy (ME) of 2,648 ft. lbs. The figures at 200 yards are 2,263 fps and 1,705 ft. lbs.
The 165 grain spitzer bullet is loaded to a MV of 2,700 fps and a ME of 2,679 ft. lbs. At 200 yards the velocity is 2,194 fps and the remaining energy is 1,763 ft. lbs.
The 180 grain spitzer bullet leaves the muzzle at 2,620 fps with 2,743 ft. lbs. of energy. At 200 yards it is traveling at 2,178 fps and has 1,898 ft. lbs. of kinetic energy.
There are also premium factory loads that are loaded a little bit hotter. Many of the ammunition manufacturers now offer these loads. For example, Federal's Premium High Energy load for the 165 grain bullet has a MV of 2,870 fps and a ME of 3,020 ft. lbs. Their 180 grain load drives a Nosler Partition bullet at a MV of 2,740 fps and a ME of 3,000 ft. lbs.
Hornady's Light Magnum loads are the fastest on the market. One Light Magnum load drives their 150 grain spire point bullet at a MV of 3,000 fps and ME of 2997 ft. lbs. The other Hornady .308 Light Magnum load drives the 165 grain boat-tail spire point bullet at a MV of 2,880 fps and a ME of 3,038 ft. lbs. These loads really get about all that can be gotten out of the .308 Winchester, and reloaders will be hard pressed to duplicate them.
Let's take a look at the trajectory of a couple of typical .308 hunting loads. If you zero a scoped .308 rifle to put a typical 150 grain spitzer bullet at a MV of 2800 fps 2.7" high at 100 yards it will strike about 3" high at 135 yards, 1.7" high at 200 yards, and 3" low at 275 yards. A 180 grain spitzer bullet at a MV of 2,610 fps will hit about 2.8" high at 100 yards, 3" high at 125 yards, 1.2" high at 200 yards, and 3" low at 259 yards.
Remember, though, if your rifle has a barrel shorter than 24 inches your velocity will be less than the figures shown in the ballistic tables. Of course, that is also true for the other all-around calibers, the factory ballistics for all of them are normally established in 24 inch test barrels. Regardless, the .308 Winchester obviously has what Jack O'Connor once called "big punch in a small case."
Copyright 2001, 2012 by Chuck Hawks. All rights reserved.