Most Accurate 556 Ammo For SBR Rifles

With the growing interest in short barreled firearms and Personal Defense Weapons, there’s an equally growing demand for ammunition to run through them.

Sure, SBR rifles and AR Pistols carry easily and stow in tight spaces, but is the juice worth the squeeze?

How short can you go while maintaining accuracy and adequate terminal performance? Will your ammo of choice perform adequately from an 10.5", 7.5", or even a 5.5" barrel?

Most Accurate 556 Ammo For SBR Rifles
5.56 NATO SCS® (TUI) ammunition is designed for light recoil with no sacrifice in velocity.

In a defensive situation, you need ammunition that can deliver adequate penetration and expansion at a reduced velocity. Further, depending on the situation, the ammo needs to be able to handle barriers like windshields or walls, and have the ability to "buck" the wind or light foliage at distance.

The two most common types of ammo are the 55 grain M193 and 62 grain M855. Let’s take a closer look at those two loads.

M855 vs M193

Are M855 and M193 good options for an SBR rifle or AR pistol?

Full metal jacket projectiles are dependent on fragmentation for increased wounding capabilities, and fragmentation is, for the most part, dependent on velocity.

The velocity of 5.56 is severely affected by shorter barrel lengths. So much so that when fired from a short barrel, some versions of the NATO round won’t reliably fragment once they’ve exited the muzzle.

Now, this is not to say that SBR rifles and AR Pistols are useless with M855 or M193. Far from it.

  • M855 is better at barrier penetration
  • M193 is better suited for soft targets under 100 yards
  • M193 prefers a 1:9 twist rate, while M855 prefers a 1:8 or 1:7 twist rate


at Kentucky Gun Co
Prices accurate at time of writing

If you get shot with a 5.56 bullet of any type, you’re gonna have a pretty crappy day. But if we want maximum terminal effects on target, we’re going to need a bullet that does something other than just make a hole in whatever it impacts.

That is where pairing the right barrel twist rate with the right ammunition is key. Similar to pairing scotch with a cigar, if you pair up the wrong ones, you’re going to have a poor experience.

Related Article – M855 vs M193 | Which One Should I Buy?

What about Barrel Twist Rate?

The stamp on the barrel itself should indicate the barrel twist after the caliber.

The most common ratios are 1:7, 1:8, 1:9, and 1:12. This means that the barrel will spin the bullet one revolution every X inches.

What is the ideal barrel twist rate?

Bullet WeightPreferred Barrel Twist Rate
55 Grain1:9
62 Grain1:8 followed by 1:7
77 Grain1:7 followed by 1:8


The most common 556 ammo, 55-grain and 62-grain, are fine to shoot in 1:7 to 1:9 barrels. You probably won’t even notice a difference until you get out past 300 yards, but with a short barrel such as the Maxim Defense PDX, you’re not going to be reaching out that far anyway.

Maxim Defense PDX

Best SBR Ammo for the Maxim Defense PDX

As technology in the shooting industry evolves, so do the manufacturers. One of those manufactures on the leading edge of this evolution is Maxim Defense Industries.

Their award-winning PDX platform has been a game-changer in the SBR and AR Pistol market. Most commonly, you’ll see barrel lengths in this category range from 7.5" up to 14". Maxim Defense took the market to another level by incorporating a 5.5" barrel into the PDX platform.

Maxim Defense PDX

Prices accurate at time of writing

Regardless of the extremely short length, Maxim Defense has engineered the barrel to be both reliable and accurate for its users.

  • The barrel twist rate of the PDX chambered in 5.56 is 1:7 (178mm)
  • The preferred load for the 5.5" barrel with a 1:7 barrel twist rate is the NATO M855 62gr ball
  • Using the NATO M855 62gr ball ammo with a 1:7 barrel twist rate results in a max effective range of 200 yards for the PDX platform

5.56 NATO 55 Gr Short Barrel Ammunition

at Maxim Defense
Prices accurate at time of writing

Most Accurate 556 Ammo [That’s Actually Available]

Based on what we’ve covered up to this point, we’re going to stick with 55 grain and 62 grain that meet NATO standards.

The following ammo selections are also all brass cased, so you can keep the spent brass and reload your ammo if you choose to do so.

Related Article – Hands-On Beginner’s Guide to Reloading

Winchester M855

Winchester M855

at Kentucky Gun Co
Prices accurate at time of writing

PMC X-Tac 62 Grain Full Metal Jacket Green Tip

PMC X-Tac NATO 5.56

at Brownells
Prices accurate at time of writing

Norma Tactical 62 Grain SS109 Steel Core

Norma Tactical 62 Gr SS109

at TrueShot
Prices accurate at time of writing

American Eagle XM193

American Eagle XM193

at Kentucky Gun Co
Prices accurate at time of writing

Related Article – Best Places To Buy Ammo Online | Ammo Seek


So there you have it, our recommendations for the most accurate 556 ammo out of an SBR.

Let us know in the comments what you use!

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