The .308 Winchester (.308 Win) and 5.56 NATO rounds are two of the most popular centerfire rifle cartridges in the United States and across North America. Both cartridges are battle-proven and currently in service with the U.S. Military and its NATO allies.
The 308 vs 556 debate has been raging between civilian marksman, law enforcement, and military shooters for well over 60 years and is akin to a clash of heavyweight titans nothing short of Ali vs Frasier.
Sufficed to say, it is unlikely that we will be able to crown a victor in the context of this article.
However, get ready for an absolute knock-down, drag-out, slugfest between two of the most popular and iconic cartridges in shooting!
A Quick Note on Nomenclature
In the context of this article, .308 Winchester (308 Win) and 7.62x51mm NATO (762 NATO) will be used interchangeably. The same can be said for .223 Remington (223 Rem) and 5.56x45mm NATO (556 NATO).
However, please understand that rifles chambered in 308 and 223 are different than those chambered in their NATO spec equivalents, 762 and 556, respectively.
It’s important to note that NATO spec ammunition should ONLY be fired from rifles chambered to NATO specifications.
You should experience zero issues shooting .223 Rem ammo in your 5.56 rifle, but not vice versa. The same is true for .308 in a 7.62 rifle. This is due to chamber pressure differences between the .223 vs 5.56 and .308 vs 7.62 rounds.
Bottom line: Know what round your rifle is chambered in (it’s typically engraved on the barrel or receiver of your rifle).
What is .308 Win?
Following the end of the Korean War, the U.S. Military started developing a replacement for the storied M1 Garand. Although the M1 Garand had served the U.S. Armed Forces valiantly through World War II and Korea, the military wanted a more modern service rifle with select-fire capability and detachable magazines similar to the Stg-44 and AK-47.
The M1 Garand was chambered in the 30-06 Springfield cartridge, 7.62x63mm NATO designation, a round that has been credited with taking down every North American large game animal, including the great bears.
With advancements in rifle powder technology and case design in the 1950s, the new 7.62x51mm NATO rifle round was able to achieve neatly identical ballistic performance as the 30-06 Springfield with a shorter cartridge case length and lower overall weight.
The US Army officially adopted the 7.62x51mm NATO round and the new M14 battle rifle in 1958. The M14 featured a 20-round detachable magazine and select fire capability (semi-auto and full auto).
The M14 saw its first action in the Vietnam War before being quickly being replaced by the M16 in 1964.
762 has also been utilized in multiple machine guns fielded by the U.S. Military, including the M60, M240B, and GAU-17/A minigun.
Seeing the potential of the 762 in the civilian market, Winchester was quick to adapt the new rifle round to its Model 70 bolt action rifle. The civilian version of the 7.62 was named the .308 Winchester.
Other major firearms manufacturers followed suit and the 308 Winchester quickly became available in multiple bolt action, pump, and semi-automatic rifle platforms.
Other popular 308 Winchester bolt action rifles include:
- Savage 11/110
- Remington 700
- Ruger M77 Hawkeye
- Browning X-Bolt
- Weatherby Vanguard
The 308 Winchester has since become the most popular big game hunting round in the world with bullet weights typically ranging between 120 to 180 grains.
With astounding accuracy, stopping power, and an effective range out to 1,000 yards (with appropriate loadings), the 308 is a staple in deer hunting camps and in marksmanship competitions across the globe.
What is 5.56 NATO?
The 5.56x45mm NATO cartridge was derived from the .223 Remington (which itself descended from the .222 Remington). Development of the 223 Rem rifle round began in 1957 and the final design was submitted by Remington Arms to the Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) in 1962.
The development of the 223 Remington cartridge was a joint operation organized by the U.S. Continental Army Command between Fairchild Industries, Remington Arms, and Eugene Stoner of Armalite.
Eugene Stone was the primary inventor of the AR-10 rifle (chambered in 7.62), which he was invited to scale down to accommodate the new .223 Rem cartridge.
The resulting rifle was the AR-15, which has become the most popular sporting rifle design in the United States. The military adopted a select-fire version of the AR-15, designating it the M16 in 1964.
FN Herstal developed the 5.56x45mm round beginning in 1970 using the 223 as a parent case. The 5.56 and .223 cases are identical in case dimensions.
However, the primary difference between the two cartridges is the maximum pressure allowance for the rifle rounds.
SAAMI specifications for the .223 Rem indicate that a maximum allowable chamber pressure of 55,000 psi. However, the 5.56 case was designed to handle pressures up to around 61,000 psi.
This is why you should NEVER fire 5.56 from a firearm chambered in .223 Rem, as the chamber a rifle chambered in 223 Remington is not rated to handle the pressure of a 5.56 round.
The 223 was quickly adopted to both AR platform and bolt action rifles from all major firearm manufacturers. Its low recoil impulse and flatter trajectory makes it ideal for marksmanship trials and varmint hunters.
As the .223 Remington ammo can be purchased in a variety of bullet weights for a variety of different applications, but the most common bullet weights that you’ll find in most all gun shops and sporting goods stores are 55, 62, and 69 grain.
Continue reading Caliber Comparison: Understanding the Difference Between 308 and 5.56 on Ammo.com
