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  • Post last modified:April 9, 2023

In this article, we are briefly comparing the 300 blackout vs 5.56 NATO to help AR15 builders making a sound decision when picking a caliber platform.

When it comes to comparing 300 Blackout and 5.56 NATO, there are several distinguishing factors including:

  • Bullet weight performance
  • Ballistics performance based on barrel lengths and twist rate
  • Knock down power VS velocity
  • Cost -  Can you burn through ammo without breaking the bank?

300 Blackout AR15 Usage

300 blk rounds

Main Attraction - The 300 Blackout is a modern round designed for a 9" short barrel carbine applications with suppressor. It's an AR and AK hybrid to shoot 7.62 alike round that delivers more energy up close. 

300 aac ballistics

Referenced The Firearms Blog

A subsonic 300 Blackout round is significantly more powerful than subsonic 5.56, 9mm, and even .308. It delivers the punch and it's the most quietest caliber while suppressed.

ddm4 300s upper

A 300 Blackout AR15 uses all the same parts as a 5.56 AR15 except for the barrel.

Most common 300 AAC bullet weight:

  • 78 gr
  • 110 gr
  • 125 gr (Most Popular)
  • 147 gr
  • 220 gr

Cost - Standard 147gr 300 AAC costs about $0.56-0.8/rd (Tons of reload kits available, but empty shell casings are hard to find on most ranges)

Shooting Experience - While the low recoil sensation is an attraction for AR15 users. The round also provides increased accuracy due to its subsonic ammunition design.

On the other hand, the 5.56 NATO is an older round with a higher recoil, greater muzzle velocity and stopping power that makes it ideal for rifles with long barrels. 

Ballistics performance - The 300 Blackout has an effective range of up to 300 meters while the 5.56 NATO can reach out to 600 meters or more with good accuracy depending on barrel length.

When fired from a 9-inch barrel, the 300 blackout produces approximately 1,000 ft/lbs of energy while the 5.56 NATO produces roughly 1,250 ft/lb from a 20-inch barrel configuration which gives it a slight edge in power.

For shooters looking for maximum firepower within their standard AR-15 platform, the 300 Blackout provides improved accuracy and less recoil than either traditional .223 Remington or 5.56 NATO rounds making it an excellent choice for close quarters scenarios such as home defense. 

5.56 NATO AR15 Usage

5.56 M855

Main Attraction - The 5.56 NATO rounds are very popular and are readily available to buy. This caliber is an excellent choice range practice, precision mid range shooting, home defense and general purpose use.

5.56 ballistics

Referenced The Firearms Blog

If you’re shooting from longer distances where accuracy matters more than terminal effect then the 5.56 NATO will provide tighter patterns at distances beyond 200 yards and better penetration through barriers such as plywood walls or car doors at 400 yards or further. While the 300 Blackout rounds fall short on range.

zeroing mk18 elcan specterdr

Most common 5.56 bullet weight:

  • 40 gr
  • 55 gr (Most popular)
  • 62 gr
  • 77 gr

Cost - Standard 55gr 5.56 or 223 costs about $0.45-0.5/rd ((Tons of reload kits available, very easy to find empty 223 or 5.56 shell casings at most ranges)


Many 5.56 BDC Reticle Optics Available - Currently, There are more 5.56 NATO calibrated scope options than 300 BLK

Main Takeaway

AR builders should pick whichever cartridge best suits their particular needs:

  • For high volume range training - Go with 5.56 NATO
  • For maximum gunshot suppression - Go with 300 BLK
  • For CQB personal defense - Go with 300 BLK