The .300 blackout vs. 308 Analysis

The 300 blackout vs. 308 is a discussion touching on two rifle cartridges that are both great performers in their own respects. Proponents for both rounds have got valid reasons as to why they have stuck to their calibers of choice and aren’t planning to shift allegiance no matter what. Though some may claim that one is more superior to the other, the truth is that both have their own benefits and limitations. It is worth noting that none of them is the one-product-serves-all type. Below is a detailed comparison between the two cartridges, that you can guide you to make an informed decision.

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1. The 300 Blackout

The .300 Blackout round of ammo, also known as 7.62×35mm is ammo designed to achieve similar ballistics to those of the 7.62×39mm cartridge while using a standard AR-15 magazine in the AR-15 platform. It was developed by Advanced Armament Corporation to be used in the M4 Carbine. When buying such calibers, be careful not to use them in the 7.62×40mm chambered rifles or any other.

There was a need amongst military circles to have ammo that performs better than the 5.56×45mm NATO when it comes to high-energy standard velocity requirements, but with a subsonic performance that is better than that of the standard 9mm. Such a need led to the development of the 300 Blackout, which can rightfully be referred to as a hybrid of the 5.56×45mm NATO and the 9mm cartridge. While designing the cartridge, the M4/M16 was kept in mind all through the process.

Ammo Anatomy

The ammo features a 221 Fireball/.223 Remington parent case. This case is the rimless, bottleneck type. The bullet diameter is 7.8mm, neck diameter of 8.5mm, 9.6mm base diameter, 9.6 mm rim diameter, 34.7 mm case length and 57 mm overall length. Its maximum CIP pressure rating is 62,366 PSI and 55,000 PSI SAAMI maximum pressure.


300 Blackout Ballistics

300 Blackout Ballistics

The cartridge produces an estimated maximum effective combat range of about 503 yards for the 125 grain supersonic. The cartridge produces up to about 2,960 ft/s muzzle velocity and up to about 2,960 ft/s energy.

At their full magazine capacities, the cartridge has been able to produce energies similar to those of the 7.62×35mm Soviet with the AR15 platform.

The .300 BLK is easier to work with, especially due to the fact that its rifles out uses almost all the same parts used by the popular AR15. You can easily interchange the bolt, magazines and gas systems without any changes. As long as your gun is not the short barrel rifle, any part can be swapped between these two platforms.

In addition to the versatility, by just trimming off around ¼ to 1/3 of the 5.56mm parent case, you get the reloading bonus that eventually cuts the cost of the cartridge by almost half.

2. The .308 Winchester

The .308 Win on the other side is a rimless bottlenecked cartridge. The 7.62×51mm NATO cartridge was derived from this round. Today, this is the most popular and commonly used short-action cartridge for big game hunting in the world. Other uses include target shooting, civilian hunting, Palma, military sniping, police sharp shooting, bench rest target shooting and Metallic Silhouette. It is its relatively shorter casing that has made the cartridge to well adapt with the short-action rifles.

Ammo Specifications

It features a .300 Savage parent case that is rimless, bottleneck type. The bullet diameter is 7.8 mm; neck diameter is 8.72 mm, 11.53 shoulder diameter, 11.96 mm base diameter and 12.01 mm rim diameter. Its rim thickness is 1.37 mm; case length is 51.18 mm and the overall length being 71.12 mm.


One area where this cartridge outdoes the 300 BLK is its high terminal performance capabilities. When a bullet that fragments, tumbles or expands is loaded in the casing, the terminal performance will be one of the most impressive you have ever encountered.

The main reason why the .308 cartridge is sought after is because of its power. The only limitation that comes with the ammo is that it only works with the AR-10 platform. It isn’t as AR-15 compatible as the 300 BLK is. The punch that a target gets when hit by this cartridge is devastating even at a slightly stretched battlefield. Its effective range stands at 800 meters, surpassing the 300-meter effective range of the 300 BLK.

What do you want to do with your rifle?

Upon answering such a question, you will be able to know which one between the two would offer the best performance.

When it comes to home defense, a preferable option would be the .300 blackout vs. 308. There are those who talk of using the .308 Win for home defense. This is not a bad option for home defense if you live in a compound with walls that are three feet thick. You should also not have any pets, neighbors or even family. Realistically speaking, that is impractical.

In other words, when you live in tight spaces, which is almost always the case during this 21st century, the 300 BLK is a better solution for wielding in such tight spaces and effective enough to stop an aggressor.

Why the 300 BLK for Home Defense

There are a number of reasons that qualify the 300 BLK as the better option for home defense. Within the 300 BLK category, are found subsonic ammunitions. This means that you will not need to have ear guards on as you make your house clear from intruders. This is not the same as the .308 as this caliber comes with relatively louder noise.

When choosing a cartridge, you also need something that will keep your safe from those conditions that result after shooting. One such worry lies on the flush that results from the gun powder. The best between the two is the .300 blackout vs. 308. This is because all pistol powder is always burnt thus almost completely eliminating the muzzle flashes.

Pricing and Availability

The 308 Win is a bit cheaper than the 300 BLK. It costs slightly less than a dollar per round, whereas the 300 BLK costs slightly more than a dollar. However, it is worth noting that the 300 BLK is highly reloadable thus significantly reducing the overall costs, especially if you are a hand loader. But when it comes to availability, both the cartridges can be said to be relatively very available, though the 308 bullets are a bit more available than the 300 BLK.

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Pros and Cons of 300 Blackout Vs 308

The 300 BLK

  • It is a very good solution for home defense
  • Uses the same magazine as your 556 hence no need to spend more and carry more weight as you get into the woods
  • Produces great results with a suppressor
  • Perfect Short Barrel Rifle performance


  • It is relatively expensive ammo
  • The bullet drop is averagely significant for long distance on the 300 blackout vs. 308

The 308

  • Great performance for longer distance shooting
  • Good performance with suppressor
  • Produces better performance when hunting bigger game
  • It is cheaper ammo


  • It is a heavy piece of ammo
  • It isn’t the best bet for home defense
  • The hardware for the corresponding AR10 rifle is hardly compatible with those of the more readily available AR15.


From the characteristics and features mentioned above, it is clear that the 300 blackout vs. 308 discussions only comes to a conclusion at the jury’s level and you are the jury. It all narrows down to what you want to use the cartridge for. Both of them are good in their own respects.

The 308 happens to be the most popular hunting cartridge not only in the USA but also beyond. The main reason why people like it is because of its punching power, long range accurate performance, and availability. On the other hand, though not the most popular among the home defense ammo, the 300 BLK performs better than the 308 for such home applications.


The only main reason why the 300 BLK can end up being more preferred to the 308 is the fact that one can easily modify their AR-15 and continue using the rifle as it is with their newly preferred ammo.

As far as all the other factors are concerned, it is what you want to do with the gun and ammo that will determine what is best for you. Whereas one is a great home defense rifle, the other enables you to be coming back home with bigger game meat more frequently.

Similarly, whereas the 300 BLK will produce efficient results when used to bring down targets within 300 meters, the 308 produces quality results when you are shooting targets up to 800 meters away. The question is, "do you always shoot targets beyond 200 meters?"

In a nutshell, know what you want to use your rifle for before making the decision of whether to use the 300 blackout vs. 308 or not.

7 thoughts on “The .300 blackout vs. 308 Analysis”

  1. .300 BLK is just another marketing plan to sell the next wave of gear. If you are staying under 300 yards, the AR is fine. Use a 64+gr bullet and quit using ridiculously short barrels!
    I opted for 6.8 since it actually solves the M193/855 problem and out to a greater distance. You referred to the Military’s definition of effective range, which we all know is a stretch. And the question, “do you always shoot targets beyond 200 meters?” again makes the AR a sufficient option. Barrier blind loads are available that can be used against windshields and still be lethal.
    I am sure the 300 BLK is fun to shoot, but it is not needed for civilian use. It may keep gun writers busy, but 300 BLK is really just for fun.

  2. The 300 Blk will surely have a following. Count me in! Years ago 6.8 came up and I said no. I’ll shoot heavier 5.56 bullets for harder target. Stumbled up on a 300 Blk upper for the right money and got it. It was fun to shoot, and better in short barrels than 223. So I had a 10.5 inch pistol built. They got me with the 300 Blk. Now it’s CAN time.

    We’ll see if more gun gear stuff catches on. 224 Val and the Wilson Ham’r, but I think 300 Blk is here to stay

  3. The right tool for the job.
    223- 16″, 20″, 24″
    300 Blk- 16″ and 10.5 ” Pistol
    308- Rem 40X Target, Vore Hunting Rifle, Armalite AR-10

  4. No one has been able to tell me if the 308 bullet is the same size as the 300 Blackout bullet. Not total just size of the bullet.

  5. Not an expert at all on this stuff, just learning myself……………..BUT, the .308 bullet is the bullet you use in the 300 aac brass. Do yourself a favor and get yourself a resizeing die for the 300 aac. You can save yourself a lot of money by making your own brass by trimming a 223 / .556 caseing to length and resizing it in a 300 aac die.
    You can save yourself a bunch and be able to shoot more on a small budget.

  6. 300blk is a .223 case necked up to accept a .308 bullet, you can run ANY .308 bullet you want. I have done supersonic 125g up to 240g, and subsonic 180g to 240g. Reloaders who casts his own bullets can shoot 300blk virtually for pennies a round. pickup spent .223 brass at the range and cut them down to form into 300blk, cast your favorite 30cal bullet and load up, all you need to buy is primers and powder.


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