June 23rd, 2024
7minute read
There are many classic debates such as Ford or Chevy?
9mm vs. .45 ACP?
5.56 vs. 300 Blackout?
Which chambering do you want for your AR-based firearm — 5.56 NATO or 300 BLK?
The debates never end.
The caliber disagreements often persist because theres usually a nugget of truth in the arguments for either side.
Then theres the issue of context.
The 300 BLK cases (left) are cut-down .223 cases reshaped to handle the larger.30-caliber bullets.
Is a pistol better than a rifle?
For concealed carry it probably is while for home defense, the rifle might be the better choice.
Lets take a closer look at the 5.56x45mm NATO vs. 300 BLK question.
In loaded cartridges, much of the projectile is hidden inside the case. From left to right: 55-gr. .224, 77-gr. .224, 125-gr. 300 BLK and a 245-gr. lead subsonic 300 BLK bullet.
What Is 300 Blackout?
The first goal seems easy, right?
Why not just make an AR-15 upper receiver chambered and barreled for the ubiquitous 7.62x39mm centerfire ammunition?
For starters, that would be copying from our enemies and that strategy is kind of lame.
More importantly, those heavily tapered cartridges dont feed from standard AR magazines.
What Is the .300 AAC Blackout?
The 300 BLK actually is a cut-down version of the .223 Remington.
Think of it a bit like a standardized wildcat cartridge.
The ramifications of that are important as well see in a hot second.
From left to right: 55-gr. .223, 77-gr. .223, 125-gr. 300 BLK and 220-gr. subsonic 300 BLK.
The case dimensions are identical as is the diameter of the case body.
While the shape varies, the overall lengths are compatible, too.
Platform Differences?
In fact, all you have to do is change the barrel.
Thats a simple operation on an AR rifle or pistol.
Once you remove the barrel nut, it just pops out for an easy swap.
Since the cartridge base is identical, the bolt and bolt carrier are unchanged.
In other words, use any AR-15 bolt carrier group you like.
For the same reason, the magazines are interchangeable too.
Oh, theres one more benefit.
Unlike different AR cartridge offerings like 6.8mm Remington SPC, capacity of magazines is also identical.
A 300 Blackout round will feed into a .223 Rem or 5.56 NATO chamber.
Be careful to not mix your ammo and magazines!
What About Energy of the 300 Blackout vs. 5.56?
Downrange Performance Is 5.56x45mm NATO or 300 AAC Blackout Better?
One notable difference between 5.56 and 300 BLK is bullet mass (or weight).
Typical 5.56 NATO projectiles weigh somewhere between 55 and 77 grains.
The most common supersonic 300 BLK loads use 110- or 125-gr.
The subsonic ammunition normally load 220-gr.
This creates a tradeoff.
The cost is more bullet drop.
So, the right choice for you depends on what you care about more.
Both pistols were set up with a 50-yard zero.
I only included the subsonic 300 BLK data at 300 and 500 yards for consistency.
We didnt want that elegant table of data points to have big gaps in it, now did we?
Although, assuming one can hold high enough to account for that 377-inch (thats 31 feet!)
[Dont missCan You Shoot 223 out of a 556 Rifle.]
Subjective Factors
Bullet weight matters if youre looking to maximize energy on target.
While the classic kinetic energy measurement of ft-lbs.
So, if youre looking for a harder hit, the BLK offering might be right for you.
On average, 55- and 77-gr.
5.56 bullets deliver 22 to 28 pounds-feet per second of momentum at the muzzle.
300 BLK projectiles carry 36 and 33, give or take.
Ammo cost is also something to consider.
The 5.56 NATO world benefits from the sheer quantity of rounds fired.
That drives down the cost per round for you and me.
As a lower-volume caliber, youll generally pay more per round for both supersonic and subsonic 300 BLK cartridges.
For the same reasons, law enforcement may consider the cartridge for suppressed weapons.
Whats right for you?
Thats a bit like asking whether you prefer four-wheel drive or two.
They both have pros and cons for their respective applications.
Which one is right for you depends on exactly how you intend to use it.
In the case of 300 Blackout vs. 5.56mm NATO, both are suitable for defensive purposes.
For larger game where penetration is more important, the BLK presents a better overall solution.
The bottom line is this: light and fast versus slower and heavier.
Sounds kind of like the9mm vs. .45 ACP debate, doesnt it?
hey ensure you are up-to-date on all current laws.
