300 Blackout and 5.56 NATO both run in the AR-15, both use the same bolt and magazines, and both are excellent cartridges. But they are built for different jobs. 5.56 fires a small, fast bullet that shoots flat and reaches out to several hundred yards. 300 Blackout fires a heavier .30-caliber bullet that performs well from short barrels and shines with a suppressor, especially with subsonic ammo.
This guide compares 300 Blackout vs 5.56 side by side, with a ballistics chart, effective range, energy, recoil, home defense and hunting considerations, ammo cost, and the one safety rule every owner of both must follow.
300 Blackout vs 5.56: The Quick Answer
- Choose 5.56 if you want a flat-shooting, affordable, do-everything AR-15 for training, home defense, varmints, and shooting out to 500 yards.
- Choose 300 Blackout if you want a short-barreled rifle or AR pistol, plan to shoot suppressed, want quiet subsonic loads, or want a heavier bullet for hogs and deer at close range.
- Many shooters own both. Because only the barrel changes, a second upper is an easy way to add 300 Blackout to an existing AR-15.
300 Blackout vs 5.56 at a Glance
| 5.56×45 NATO | 300 AAC Blackout | |
|---|---|---|
| Introduced | 1960s with the M16 (NATO standard in 1980) | 2011 (SAAMI approved January 2011) |
| Developer | Based on .223 Remington | Advanced Armament Corp. (AAC) with Remington |
| Bullet diameter | .224 in | .308 in |
| Common bullet weights | 55 to 77 grains | 110 to 125 grains supersonic, 190 to 220 grains subsonic |
| Typical velocity (16-inch barrel) | About 3,000 fps (55gr) | About 2,200 fps (125gr), about 1,000 fps (220gr subsonic) |
| Typical muzzle energy | About 1,100 ft-lbs (55gr) | About 1,360 ft-lbs (125gr), about 500 ft-lbs (220gr subsonic) |
| Practical effective range | About 500 yards | About 300 yards supersonic, about 100 to 150 yards subsonic |
| Best barrel length | 14.5 to 20 inches | 8 to 16 inches |
| Suppressed performance | Good, still loud with supersonic ammo | Excellent, especially with subsonic ammo |
| AR-15 parts that change | None | Barrel only (same bolt and magazines) |
What Is 5.56 NATO?
5.56x45mm NATO is the military version of .223 Remington, adopted by the U.S. military with the M16 in the 1960s and standardized by NATO in 1980. It fires a light, fast .224-caliber bullet, typically 55 to 77 grains, and it is by far the most common AR-15 cartridge. Huge military and commercial production makes it one of the cheapest centerfire rifle rounds to shoot.
If you are still sorting out the difference between 5.56 and .223, see 5.56 vs .223: 19 Things You Need to Know.
What Is 300 Blackout?
300 AAC Blackout was developed by Advanced Armament Corporation with Remington Defense, with most of the work done in 2010. SAAMI approved it in January 2011. The goal was to fire .30-caliber bullets from the M4 and AR-15 platform using standard bolts and magazines, with full magazine capacity, better performance than 5.56 from short barrels, and effective subsonic performance for suppressed use.
The case is a shortened, necked-up .223 Remington case, so it fits the AR-15 bolt face and magazine. 300 Blackout burns its powder efficiently in short barrels, so a 9-inch barrel gives up much less velocity than it would with 5.56. That makes it a natural fit for short-barreled rifles and AR pistols.
Safety First: Never Mix 300 Blackout and 5.56
A 300 Blackout cartridge can chamber in a 5.56 or .223 rifle, and firing it can destroy the rifle and injure the shooter. The .30-caliber bullet is far too large for the 5.56 bore, so pressure spikes dangerously. SAAMI lists this as an unsafe combination.
If you own both calibers:
- Clearly mark 300 Blackout magazines and uppers with paint, tape, or different colored magazines.
- Store the two calibers separately, and never mix loose rounds in the same bag or can.
- Check every round as you load a magazine, especially subsonic 300 Blackout, which uses long bullets that look different from 5.56 but can still be mistaken in low light.
300 Blackout vs 5.56 Ballistics Chart
The chart below compares common loads from a 16-inch barrel with a 100-yard zero and a 10 mph full-value crosswind. The subsonic 300 Blackout load uses a 50-yard zero, which is typical for that ammo.
| Load | Muzzle Velocity | 100 yd Drop | 200 yd Drop | 300 yd Drop | 400 yd Drop | 500 yd Drop | Wind Drift at 300 yd | Energy at 300 yd |
|---|---|---|---|---|---|---|---|---|
| 5.56 55gr FMJ | 3,000 fps | 0 in | -3.6 in | -14.2 in | -34.2 in | -67.4 in | 13.2 in | 453 ft-lbs |
| 5.56 62gr M855 | 2,900 fps | 0 in | -3.7 in | -14.0 in | -32.6 in | -62.3 in | 10.6 in | 572 ft-lbs |
| 300 BLK 125gr OTM | 2,215 fps | 0 in | -7.3 in | -25.4 in | -57.2 in | -106.0 in | 12.7 in | 711 ft-lbs |
| 300 BLK 220gr subsonic | 1,010 fps | -7.3 in | -49.6 in | -130.6 in | -252.7 in | -418.2 in | 7.9 in | 414 ft-lbs |
Calculated using typical published velocities and G1 ballistic coefficients (5.56 55gr .243, 62gr .304, 300 BLK 125gr .366, 220gr .608), 1.5-inch sight height, standard atmosphere. Your barrel length, ammo, and conditions will change these numbers.
The chart shows the trade-off clearly. 5.56 shoots much flatter. At 300 yards it drops about 14 inches, compared with about 25 inches for supersonic 300 Blackout and more than 10 feet for subsonic. But the heavier 300 Blackout bullet carries more energy at 300 yards than either 5.56 load.
Power and Effective Range
At the muzzle, a 125-grain 300 Blackout load produces about 1,360 ft-lbs of energy, compared with about 1,100 ft-lbs for 55-grain 5.56. The .30-caliber bullet also makes a larger wound channel with the right expanding bullet design.
5.56 has the range advantage. Its flat trajectory makes hits easier at 300 to 500 yards, and heavier match bullets like the 77-grain OTM extend that range further. 300 Blackout is best inside 300 yards with supersonic ammo. Subsonic 300 Blackout drops so steeply that it is practical only to about 100 to 150 yards.
Short Barrels, Suppressors, and Subsonic Ammo
This is where 300 Blackout earns its place. Because it burns its powder quickly, 300 Blackout loses little velocity in short barrels. AAC’s published figures show a 110-grain load at about 2,300 to 2,350 fps from a 9-inch barrel, close to 16-inch performance. 5.56 loses significant velocity in very short barrels, which hurts its terminal performance.
300 Blackout also works with heavy subsonic bullets, typically 190 to 220 grains at around 1,000 fps. Subsonic ammo stays below the speed of sound, so it avoids the supersonic crack. Combined with a suppressor, that makes 300 Blackout one of the quietest rifle cartridges available. Supersonic 5.56 is still loud even when suppressed, and true subsonic 5.56 is too light to be very effective.
Running subsonic ammo reliably usually requires a suppressor or a properly tuned gas system, since subsonic loads produce less gas to cycle the action. Many 300 Blackout rifles use a pistol-length gas system for this reason.
Recoil
Both are mild. In a 7-pound rifle, we calculate free recoil at about 3 ft-lbs for 55-grain 5.56 and about 5.5 ft-lbs for 125-grain 300 Blackout. Subsonic 300 Blackout is about the same as 5.56. Most shooters notice that 300 Blackout pushes a little more, but both are easy to control, and follow-up shots are fast with either.
300 Blackout vs 5.56 for Home Defense
Both cartridges are effective home defense rounds, and the right choice often depends on your rifle.
- 5.56 is effective from a standard 14.5 or 16-inch carbine, and lightweight expanding bullets tend to fragment, which can reduce penetration through interior walls compared with heavier bullets.
- 300 Blackout is a strong choice for a short-barreled rifle or AR pistol, and with a suppressor it is much easier on your hearing if you ever have to fire indoors.
Any centerfire rifle round can penetrate interior walls, so know your home’s layout and what is beyond your target. Use quality defensive ammunition designed to expand, not FMJ range ammo, and test it in your rifle before you rely on it.
300 Blackout vs 5.56 for Hunting
300 Blackout is the better choice for hogs and deer at close to moderate range. With a quality expanding 110 to 150-grain hunting bullet, it delivers more energy and a larger wound channel than 5.56. It is a favorite for suppressed hog hunting.
5.56 excels on varmints and predators like coyotes, where its flat trajectory helps at longer ranges. Some states allow .22-caliber centerfire cartridges for deer and some do not, so check your state’s regulations. If you do hunt deer with 5.56, use a heavier bonded or controlled-expansion bullet designed for deer.
Rifle Setup: What Changes Between 300 Blackout and 5.56
Converting an AR-15 to 300 Blackout usually means swapping only the barrel, or more commonly, adding a complete 300 Blackout upper to the same lower receiver. The bolt carrier group, lower receiver, trigger, stock, and magazines stay the same.
- Barrel length: 300 Blackout performs well in 8 to 10.5-inch barrels, while 5.56 is usually best at 14.5 inches or longer. Short barrels may require a registered short-barreled rifle or an AR pistol configuration, so follow federal and state law.
- Gas system: 300 Blackout rifles typically use a pistol-length gas system, which helps cycle both supersonic and subsonic loads. 5.56 carbines usually use carbine or mid-length gas.
- Twist rate: 300 Blackout barrels are commonly 1:7 or 1:8 to stabilize long subsonic bullets. 5.56 barrels are commonly 1:7 to 1:9.
- Magazines: Standard AR-15 magazines work, though some shooters prefer magazines designed for 300 Blackout because long subsonic bullets can catch on some followers and feed lips.
300 Blackout vs 300 Whisper
300 Blackout grew out of the earlier 300 Whisper, a wildcat cartridge developed by J.D. Jones. The two are very similar, and many 300 Blackout rifles will chamber 300 Whisper, but 300 Blackout is the SAAMI-standardized version with defined specifications. Factory ammunition today is almost entirely marked 300 Blackout or 300 AAC Blackout. If you are unsure about a rifle or ammo marked 300 Whisper, check with the manufacturer before mixing them.
How 300 Blackout Compares to 7.62×39
300 Blackout is often compared to 7.62×39, the AK-47 and SKS cartridge, because both fire roughly .30-caliber bullets at similar velocities. Supersonic 300 Blackout and 7.62×39 have broadly similar ballistics. The big differences are platform and cost. 300 Blackout runs in the AR-15 with standard magazines and works far better with subsonic ammo and suppressors. 7.62×39 ammo is usually cheaper, especially steel-case loads, and is built for AK and SKS-pattern rifles.
Best Ammo Types for Each Use
| Use | 5.56 / .223 | 300 Blackout |
|---|---|---|
| Range practice and training | 55gr FMJ (M193) or 62gr FMJ (M855) | 110 to 125gr FMJ or OTM |
| Precision and longer range | 69 to 77gr OTM match | 125gr OTM match (inside 300 yards) |
| Home defense | 55 to 77gr expanding or fragmenting defensive loads | 110 to 125gr expanding defensive loads |
| Suppressed and quiet shooting | Limited options | 190 to 220gr subsonic |
| Hogs and deer | 60 to 70gr bonded hunting bullets where legal | 110 to 150gr expanding hunting bullets |
| Varmints and coyotes | 40 to 55gr polymer tip | 110gr polymer tip |
For more on the most common 5.56 military-style loads, see All About M855 Green Tip Ammo.
Cost and Availability
5.56 is cheaper and easier to find. It is one of the most produced rifle cartridges in the world, and bulk FMJ is usually among the least expensive centerfire rifle ammo per round. You can find it in nearly every gun store.
300 Blackout costs more per round, especially subsonic and premium hunting loads, and fewer stores stock a wide selection. Buying by the case helps. Shop in-stock 5.56 ammo and 300 Blackout ammo to compare current options.
Common Myths About 300 Blackout and 5.56
“300 Blackout is just a short-range novelty.”
300 Blackout is purpose-built for short barrels and suppressed use, and it does that job better than almost anything that fits an AR-15. Supersonic loads are effective to about 300 yards, which covers most hunting and defensive situations. It is a specialist, not a novelty.
“5.56 is too small to be effective.”
5.56 has served as a standard military rifle cartridge for decades. With quality expanding or fragmenting defensive and hunting bullets, and good shot placement, it is effective for home defense, varmints, and predators. Terminal performance depends heavily on bullet design and velocity, which is why barrel length matters more with 5.56 than with 300 Blackout.
“Subsonic 300 Blackout is silent.”
No firearm is truly silent. Subsonic 300 Blackout with a suppressor removes the supersonic crack and is dramatically quieter than supersonic rounds, but you will still hear the action cycle and the suppressed report. Without a suppressor, subsonic 300 Blackout is still loud.
“You need a new rifle to shoot 300 Blackout.”
Not if you already own an AR-15. A complete 300 Blackout upper installs on your existing lower receiver in seconds, and your 5.56 magazines and bolt work with it. Just keep the two calibers clearly separated.
Barrel Length and Velocity
Barrel length affects both cartridges, but not equally. 300 Blackout reaches most of its potential velocity in about 9 inches, so a short barrel gives up relatively little. AAC’s published figures show 110-grain loads at about 2,300 to 2,350 fps from a 9-inch barrel, not far below 16-inch velocities.
5.56 relies on high velocity for its terminal performance, and it loses more speed as barrels get shorter. A 10.5-inch 5.56 barrel can lose several hundred feet per second compared with a 16-inch barrel, which reduces effective range and can affect how reliably some bullets fragment or expand. That is the core reason 300 Blackout became so popular for short-barreled builds.
Which Should You Choose?
| If you mainly want to… | Choose |
|---|---|
| Train often and keep ammo costs low | 5.56 |
| Shoot past 300 yards | 5.56 |
| Hunt coyotes and varmints | 5.56 |
| Build a short-barreled rifle or AR pistol | 300 Blackout |
| Shoot suppressed with quiet subsonic ammo | 300 Blackout |
| Hunt hogs and deer at close range | 300 Blackout |
| Own one AR-15 that does everything | 5.56 |
If you only own one AR-15, 5.56 is the more versatile and affordable choice. If you already own a 5.56 rifle, a dedicated 300 Blackout upper is one of the most useful additions you can make, especially if a suppressor is in your future. Just keep the two calibers clearly separated.
Frequently Asked Questions
Is 300 Blackout more powerful than 5.56?
Yes, at close range. A 125-grain 300 Blackout load produces about 1,360 ft-lbs of muzzle energy compared with about 1,100 ft-lbs for 55-grain 5.56, and it fires a larger .30-caliber bullet. 5.56 shoots much flatter and has the advantage past about 300 yards.
Can I use the same magazines for 300 Blackout and 5.56?
Yes. 300 Blackout was designed to use standard AR-15 bolts and magazines, so only the barrel changes. Because of that, clearly mark your 300 Blackout magazines so the two calibers never get mixed.
What happens if you shoot 300 Blackout in a 5.56 rifle?
A 300 Blackout round can chamber in a 5.56 or .223 rifle, and firing it can cause a catastrophic failure because the .30-caliber bullet is too large for the bore. SAAMI lists it as an unsafe combination. Never mix the two calibers.
What is the effective range of 300 Blackout vs 5.56?
5.56 is practical to about 500 yards. Supersonic 300 Blackout is best inside about 300 yards, and subsonic 300 Blackout is practical to about 100 to 150 yards because it drops steeply.
Is 300 Blackout or 5.56 better for home defense?
Both are effective. 5.56 works well from a standard carbine and is cheaper to train with. 300 Blackout is a strong choice for short-barreled rifles and AR pistols, especially with a suppressor. Use quality expanding defensive ammo with either.
The Bottom Line
5.56 is the flatter-shooting, cheaper, more versatile AR-15 cartridge. 300 Blackout is the specialist, built for short barrels, suppressors, subsonic shooting, and close-range hunting. Choose based on your barrel length and how you plan to use the rifle. Shop in-stock 5.56 ammo, AR-15 ammo, and 300 Blackout ammo with next-business-day shipping from our Knoxville, TN warehouse.
