The 300 AAC Blackout and 308 Winchester are both 30-caliber rifle cartridges that shoot a .308” diameter bullet. However, this is where the similarities end as both cartridges have a different intended purpose.

In this caliber comparison article, we are going to take a detailed look at both the 300 AAC Blackout and the 308 Winchester. Unlike previous articles, I won’t “crown a winner” because the difference between 308 vs 300 Blackout is comparing apples to oranges.

Instead, we will take a deeper look into what the intended purpose of each rifle cartridge is and how having versatility within a caliber is a good thing for you and the 2A community in general.

I don’t know about you, but I’m ready to rack the charging handle on my AR platform and squeeze the trigger on this comparison between 308 vs 300 Blackout. Let’s close distance and ENGAGE!

308 vs 300 Blackout: A Tale of Two 30’s

As we mentioned earlier, the only similarity between the 308 Winchester and the 300 AAC Blackout is that they both shoot the same .308” diameter bullet.

Each rifle cartridge was developed for a specific role and each excels at its intended role.

However, the two rounds could not be more dissimilar, and we will explore the differences below.

300 AAC Blackout: The Dark Ops Wishlist Given Form

The development of the 300 AAC Blackout (designated 300 BLK by SAAMI) rifle cartridge began in 2010 when Robert Silvers of the Advanced Armament Corporation (which was later acquired by Remington) was approached by a member of the US Military “dark ops” community.

The unnamed military customer came to him with a problem that Silvers was eager to solve.

With the widespread adoption of the 5.56x45mm NATO cartridge (civilian ammo designation: 223 Remington or 223 Rem) for the M4 carbine, US troops were having to use the round for both long range and close quarters combat.

Overall, some special forces units were unhappy with the stopping power that the 5.56 NATO and the 9mm (used in several SMGs) offered during close quarters combat and they wanted something that had more “oomph”. Something along the lines of the 7.62x39mm Soviet round fired through the AK-47.

However, there were some other requirements that this customer required as well:

1. The rounds needed to fit into a standard STANAG AR-pattern magazine and maintain a 30-round ammo capacity
2. The cartridge face must be the same as 5.56 NATO so a bolt change was not needed
3. It had to shoot 30 caliber bullets and mimic the ballistic performance of the 7.62x39mm Soviet round
4. The new rifle cartridge needed to be compatible with short barreled rifles (SBR, barrels under 16”) and be completely functional with a suppressor/silencer
5. Both supersonic and subsonic varieties of ammo needed to be functional for long range shots as well as close quarters battle, respectively

However, Silvers was not dismayed, and he returned to AAC to begin work on a new cartridge that would meet all these needs. The search for a host cartridge had begun.

Attempts to integrate new calibers into the AR platform were nothing new to the shooting community. The adaptation of the 6.8 Remington Special Purpose Cartridge (SPC) and 6.5 Grendel into the AR platform were mildly successful; however, they fell short of the mark in several key areas.

The 6.8 SPC and the 6.5 Grendel have a larger case head than the 5.56 NATO cartridge, so a new bolt was required for the host carbine.

Secondly, although both cartridges could be loaded into a standard capacity AR-15 magazine, they could not be loaded to 30 rounds because of the increased case size.

Colt Firearms and other manufacturers had been unsuccessful in adapting a 30-caliber cartridge to the M4 carbine. Complicating matters, the M4 cannot be easily modified to simply shoot 7.62x39 Soviet either as the severe case angle causes multiple chambering issues using a standard M4 magazine.

As Silvers continued his hunt to find a proper host cartridge for his new round, he started looking at different wildcat cartridges in the shooting community.

The 300 Whisper was probably the best wildcat cartridge that Silvers encountered, and it eventually became the host for the 300 BLK. That being said, the 300 Whisper could not simply be adapted to be fired from an AR platform because it did not have standardized loadings with SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute).

As AAC/Remington was a SAAMI company, it could not load 300 Whisper ammo. Therefore, Silvers took the concepts from the 300 Whisper and modified them to meet their design specifications.

The new round was called the 300 AAC Blackout (300 BLK) and was approved by SAAMI on January 17, 2011.

300 BLK Ammo Specs

Since its approval by SAAMI in 2011, the 300 BLK has exceeded expectations in almost every category.

With an overall case length of 35mm, the 300 BLK has a case capacity of approximately 19.2 grains. The reduced case length was required to allow it to fit into a standard M4 carbine magazine while being loaded with a longer 30 caliber bullet.

300 BLK ammo can be broken down into two different bullet weights, 220 grain subsonic and 110 to 125 grain supersonic.

Supersonic ammo, typically firing a 125 grain bullet, will have a muzzle velocity of approximately 2250 fps and have a muzzle energy of around 1404 ft-lbs. Industry standards list the effective range of the supersonic 125 grain bullet loadings to be 500 yards.

In contrast, subsonic ammo will fire a 220 grain bullet and have a muzzle velocity of around 1000 fps and a muzzle energy of 488 ft-lbs with an effective range of 200 yards.

These two popular loadings really illustrate the versatility of 300 BLK ammo. With a simple magazine change, a shooter can switch from supersonic ammunition and long-range engagements to subsonic ammunition for short range combat.

Furthermore, the 300 BLK was designed specifically to experience a full powder burn when being fired in a 9” short barreled rifle (SBR), preferably with a suppressor/silencer.

308 Winchester: The Tried-and-True Warhorse

The 308 Winchester (7.62x51mm NATO designation) has been in service with the US Military for over 60 years and is the quintessential hunting round for whitetail deer to black bear.

The development of the 308 Winchester began from the needs of the US Military to advance into a new realm of battle rifles similar to the STG-44 and the AK-47.

In 1952, the U.S. Military started developing a replacement for the long-serving 30-06 Springfield cartridge (military designation: M2 Ball or 7.62x63mm).

Although the 30-06 Springfield had honorably served through both World Wars and Korea, the US Military wanted to develop a new cartridge that was lighter and more suitable for fully automatic rifle fire.

With advancements in rifle powder technology and case design in the 1950s, the new 7.62x51mm NATO rifle round was able to achieve nearly 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 in 1958 and it has been in service ever since.

Although the 7.62x51mm NATO cartridge and its parent rifle, the M14, only saw limited frontline use in Vietnam before being replaced by the 5.56 NATO, the military was quick to adapt it to use in sniper operations and in fully automatic machine gun use.

With a massive effective range out to and beyond 800 yards, it didn’t take long for civilian firearms manufacturers to take notice of the new military round.

Winchester was the first to adapt the new cartridge to its Model 70 bolt action rifle, renaming the cartridge the 308 Winchester.

The 308 Winchester quickly rose to be THE long-range high velocity hunting round that had enough muzzle energy to stop a black bear in its tracks.

Since its acceptance by the hunting and competitive shooting communities, the 308 Winchester has been a staple at deer camps and F Class Shooting Competitions alike.

308 Winchester Ammo Specs

308 Winchester ammo is available in a delirium-inducing amount of bullet weights. From 55 grain all the way up to 220 grain weight bullets, you will never lack variety when it comes to selecting the best 308 round for your purpose.

With a 51 mm overall case length, the 308 Winchester offers a whopping 52 grain case capacity. This translates to a 150 grain bullet loading have a shoulder-bruising 2820 fps muzzle velocity and a muzzle energy of 2648 ft-lbs.

300 Blackout vs 308 Winchester: The Comparison

Although these calibers are two completely different rounds with differing modes of service, I wanted to give you a quick rundown of each rifle cartridge to explain the pros and cons.

Continue reading 300 Blackout vs 308 Caliber Comparison: Why Intended Purpose Matters at Ammo.com.