Bullets weighing from 40 to 77 grains are the most popular in .223 Rem.
No cartridge has more ammunition produced for it that the .223 Remington, largely due to the popularity and the voracious appetite of the AR-15.
Bolt-action rifles chambered in this caliber also consume a lot of ammunition in pursuit of varmint control, but they pale in comparison to consumption rates of AR-15s.
Regardless of the rifle fired, there’s a lot of variety in .223 Remington and 5.56x45mm ammunition.
If you’re wondering if .223 Remington and 5.56mm ammunition are interchangeable, the answer is .223 Remington ammunition can be fired in any 5.56x45mm rifle.
Consult the owner’s manual before firing 5.56x45mm ammunition in a .223 Remington rifle.
The most popular bullet weights vary from 50 grains up to 77 grains. Here’s a look at the most common bullet weights and types and where each serves best.
.223 Remington: 40- to 50-grain Bullets
40- to 50-grain bullets are best used for varmint and pest control.
The light weight gives these bullets above average velocity, regardless of the barrel length.
Most bullets in this weight are designed for use on varmints, so they have thin jackets that help them expand rapidly on contact. I’m also a big fan of polymer tips on varmint bullets, because a polymer tip kick-starts expansion.
Combine a thin jacket with a polymer tip and throw in an extra dash of velocity, and the results can be explosive. The phrase “pink mist” was born when polymer-tipped varmint bullets weighing 40 to 50 grains made first contact.
M193 .223 Rem. 55-grain FMJ
Think of 55-grain Full Metal Jacket (FMJ) bullets in .22-caliber as the Toyota Corolla of projectiles.
There’s nothing sexy here, just good basic performance produced in massive quantities. The most ubiquitous 55-grain bullet loaded in 5.56x45mm ammunition is M193, frequently referred to as XM193 on the commercial market.
The ammunition is exactly the same, just that XM193 hasn’t gone through all the military certification processes.
Factories all around the world produce XM193, so economies of scale are why this is almost always the cheapest thing available and it is the preferred ammunition for blasting at the range and mag dumps.
M855 62-grain Green Tip .223 Rem Ammo
The second most common 5.56x45mm ammunition produced is M855, or XM855. This is also produced in massive quantities from factories around the world, but there are some significant differences between bullets in M193 and M855.
Where M193 is a 55-grain copper-jacketed lead bullet, M855 62-grain projectiles consist of a steel penetrator, surrounded by a lead core and encased in a copper jacket.
The only indicator that there is a steel penetrator inside the projectile is a dab of green paint on the bullet’s nose.
The steel torpedo-shaped penetrator in M855 is its distinguishing feature.
This bullet was designed to help penetrate light Soviet armor in the Cold War, but it is not legally classified as “armor-piercing.”
The steel penetrator makes this bullet a great choice when you want as much penetration as the 5.56x45mm cartridge can produce. The downside of the penetrator is its effect on bullet concentricity and accuracy.
Don’t accuracy-test a rifle with M855 at the risk of extreme sadness. Another thing to remember about M855: never shoot it at steel targets.
The steel penetrator in the bullet will pit the target and, if the steel target is dished, there’s a good chance the steel penetrator will ricochet back in the direction from which it was fired.
.223 Rem Heavyweights: 69- and 77-grainers
The final category of .223 Remington ammunition is 69- and 77-grain match. This is the stuff you want when it comes time to assess accuracy in a rifle.
The thin copper jacket and gracefully shaped nose ensures these bullets will center well as they enter the rifle’s bore. The thin jacket makes it easier for these projectiles to be more perfectly concentric, and that shows up as improved accuracy.
While this ammunition tends to be more expensive, there is nothing better for shooting tight groups or ringing steel at long distance.
The .223 Remington is one of the most useful cartridges around.
It’s great for varmint control, self-defense, and a fun day at the range. With broad availability and a wide variety of bullet weights and types, it’s easy to find the right load.