You probably don’t need us to tell you that the .308 Winchester is one of the most successful, influential, and overall popular centerfire rifle cartridges of all time. You may even have landed on this article before you are looking for an upper for a .308 rifle build.
So, perhaps you knew some of these interesting facts about the cartridge.
1. .308 Winchester and 7.62x51mm NATO are not the same cartridge
While the .308 Winchester was designed around the new (at the time) 7.62x51mm NATO cartridge, and bears basically the exact same cartridge dimensions, the two are not the same.
The main difference between them is that the .308 has thicker casing walls than the NATO version, and the chamber dimensions of the two are slightly different as well. The .308 Winchester also generates slightly higher chamber pressures, meaning that you can safely shoot a 7.62 in a .308 chamber, but not the other way around (the opposite of how it is with .223 and 5.56).
2. It was originally conceived as a replacement for the .30-06 Springfield that had been in use for about 50 years beforehand, and through two World Wars
The United States Army wanted to develop a cartridge that was lighter, easier to carry, and produced less recoil while still delivering similar ballistic performance to the .30-06 Springfield that the Armed Forces had carried since about the time of the First World War.
In fact, the 7.62x51mm NATO cartridge, from which the .308 was designed, used the .30-06 Springfield as its parent cartridge.
3. This cartridge delivers excellent terminal ballistics for a wide range of shooting disciplines
Depending on bullet weight and load data, the .308 Winchester can deliver muzzle velocities between 2,700 FPS and 3,100 FPS along with muzzle energies between 2.600 and 2,700 ft-lbs.
It is not as flat shooting as 5.56, but it still has a relatively decent ballistic coefficient, and is a powerful enough round to be used for hunting, as well as defensive applications, official use, and target shooting, including steel shooting and Palma shooting.
4. The short action cartridge performs well not only in bolt-action rifles but in autoloaders
One of the great things about this cartridge is its short length, which results in fast cycling times, both in autoloaders and in bolt-action rifles.
While it is not suitable for use in most lever action rifles (spitzer bullets don’t work well with tube magazines), it allows for really fast cyclic rates manually, through a bolt-action, as well as through a gas-operated action, such as what you’ll find on an AR-10 or AR-15.
5. This cartridge is much more versatile as a hunting cartridge than you might expect
It should come as no surprise to you that the .308 Winchester is widely regarded as an effective deer hunting cartridge, and delivers more than enough energy, even at several hundred yards, to cleanly dispatch pronghorns and smaller game like coyotes.
But, some hunters will also swear by this cartridge for much larger game, such as moose and elk. In fact, the Alaska Division of Fish and Game itself recommends .308 as a suitable cartridge for defense against brown bears. The Canadian Arctic Rangers even use this cartridge for protection against polar bears!
6. Some African hunters believe .308 delivers suitable hydrostatic shock to stop certain game with appropriate bullets
Water is not compressible. Blood, and tissues, are mostly water. Hence the (somewhat controversial) theory that a bullet that delivers sufficient energy can create a pressure wave that generates immediate, remote neural damage from the site of the wound - effectively incapacitating the target on contact.
It’s not universally accepted, but it has been argued that the .308 Winchester, when loaded with an appropriate bullet, can produce hydrostatic shock sufficient for dispatching African game as large as eland.
7. Despite its drooping trajectory, it far outperforms .223/5.56 at close ranges
Putting concerns associated with over-penetration aside for the time being, if you are considering a build with either an upper for a .308 or a .223, know this. The .308 has the .223 beat, hands down, on muzzle energy and stopping power, at both close and extended ranges.
Your average .223 load produces about 1,290 ft-lbs at the muzzle whereas most .308 loads generate about 2,600 to 2,700, as detailed above. You don’t have to do the math; we did for you.
8. This cartridge has been in production since 1952
The .308 WInchester cartridge is 71 years old this year, making it one of the longest lived centerfire cartridges in production, and by far one of the most popular. It’s no .30-30, and it’s no .30-06, but it’s still been around for a long time, and it still remains popular for a wide range of different shooting disciplines.
9. The .308 Winchester cartridge has served as the parent case for a wide range of other popular cartridges
The .308 Winchester isn’t just an excellent cartridge itself. It has also served as the parent cartridge for a multitude of offshoots, including but not limited to .243 Winchester, .307 Winchester, .260 Remington, 7mm-08 Remington, and .338 Federal.
10. A variety of AR platforms can be built around the .308 Winchester
The AR-10 is one platform built around the .308 and you can build your own rifle with an upper for a .308, like an AR-.308.
Another alternative if you are interested in the performance of .30 caliber cartridges (as compared to .22-caliber cartridges) is to look into the possibility of building with a .300 Blackout upper, which uses many of the same parts as an AR-15 chambered in .223/5.56, and only necessitates the use of a different barrel.
Fan of .308? Start Your Build with an Upper for a .308
Gearing up for your next home build? Get what you need here at MCS Gearup. We carry uppers for .308 rifle builds, along with lower parts kits, AR build kits, and the piecemeal parts you need to complete your project, along with tools..
If you have any questions, get in touch with us at Sales@MCSGearup.com and we will be more than happy to help.