Here Is Why 5.56×45 Ammo Is the Most Used Rifle Ammo in the US

Why is 5.56×45, aka 5.56 NATO, the most popular round in the US? Could it be because it is chambered in the most popular rifle in the US – the AR-15? Or because of its accessibility and ballistic performance? Let’s find out.

Besides answering the burning question, in this article, we will also resolve some of the most common misconceptions surrounding 5.56×45 ammo and help you recognize if this ammo type is the best fit for you.

The 5.56×45 vs .223 Rem

The .223 Rem (first named .222 Remington Special) was developed from the .222 Rem cartridge as an ammo solution for the military AR-15 (latter dubbed M14) rifle. There was a point in time when .223 Remington and 5.56×45 rounds had exactly the same specifications.

Today, these two rounds defer in many sections. They have the same cartridge case external dimensions, but the 5.56 NATO chamber has a 0.125” longer leade (the distance measured between the case mouth and the barrel rifling).

Additionally, 5.56 NATO is loaded for higher pressure than .223 Rem rounds. Because of this difference, you can load .233 Rem rounds into rifles that chamber 5.56 NATO rounds, but it is unsafe to load 5.56 NATO into rifles that are designed to chamber .223 Rem rounds.

5.56 NATO Performance

The standard 5.56 NATO is a 62-grain, steel core, spire point (spitzer) bullet round. It can penetrate 15 to 20 inches into soft tissue and has an impact velocity of 2,500 fps and above.

When the impact velocity is over 2,500 fps, the spitzer-shaped bullets will tumble and fragment upon hitting the living tissue, thus producing secondary projectiles like pieces of bone or clothing that cause a permanent wound cavity.

Though it seems smaller than some other rifle rounds like 7.62×51 NATO or .308 Win, 5.56 rounds are definitely lethal, especially when fired from 300 yards or less.

Do All AR-15 Rifles Chamber 5.56 ammo?

No, not all AR-15 rifles are made to fire 5.56 ammo. So, how do you know if your AR-15 is suitable for these rounds? Every AR-15 rifle should have a stamp on its barrel that states the type of caliber a rifle is rated to fire.

If it says 5.56 you can shoot both 5.56 NATO and .223 Rem rounds. But if it says .223 Rem, you shouldn’t load it with 5.56 ammo.

Can You Hunt With 5.56 Ammo?

Yes, 5.56 ammo is perfect for hunting small game and pest species, like coyotes or nutrias. In theory, you can also use it for whitetail hunting. But because these rounds are smaller in size and produce less energy, most states prohibit the use of 5.56 ammo for hunting big game.

Is 5.56 Ammo Good for Home Defense?

Yes, 5.56 ammo can be used for home defense as it is approved by the FBI’s conduct testing. But it is not an ideal solution mainly because it might penetrate your target and hit an innocent bystander.

Also, these rounds produce bright muzzle flashes. So, shooting at an intruder in the pitch dark can leave you blinded for some time. Let’s not forget the deafening sound that a 5.56 cartridge can make in confined spaces.

Going both blind and deaf at the same time is not an ideal situation in a home defense setting.

However, if you do decide to use 5.56 ammo for home defense opt for the hollow point or soft point bullets, as they expand more upon hitting the tissue and are less likely to go completely through the target.

Is 5.56 Ammo Affordable?

Not only is 5.56 ammo affordable, but it also comes in bulk. For instance, you can purchase 500 rounds of Winchester M855 green tip 5.56 ammo for less than $300. At the same time, a box of 20 5.56 rounds can cost you less than $10.

But the most attractive feature of 5.56 ammo is that it is readily available in most gun supply stores. So you won’t have to worry about not being able to find these rounds when you need them most.

Closing Thoughts

What makes 5.56×45 the most popular ammo in the US in the end? According to the National Shooting Sports Foundation, there are around 20 million AR-15-style firearms in the US. So this might have something to do with the popularity of the 5.56 NATO round.

But that’s just a part of their appeal. These rounds are also versatile enough to be used for both hunting and home defense. And lastly, they can be found everywhere at affordable prices.

So, do you think the 5.56 NATO rounds are for you?



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