Two cartridges in one
Understanding .300 Blackout ballistics requires thinking about it as two separate cartridges sharing one case. The .300 BLK (.300 AAC Blackout) is unique among rifle cartridges: it's designed to do two fundamentally different things from the same AR-15 platform.
Supersonic loads (110–125gr at 2,200–2,350 fps) deliver rifle-level terminal performance for home defense, hunting, and general use.
Subsonic loads (190–220gr at 1,000–1,050 fps) eliminate the sonic crack for suppressed shooting, prioritizing quiet operation over range and energy.
Same magazine. Same bolt. Same rifle. Just swap the ammo.
Supersonic ballistics
Standard supersonic loads use 110–125gr bullets at rifle velocities. Data below is from a 16" barrel.
110gr supersonic (Hornady V-MAX / Barnes TAC-TX)
| Distance | Velocity | Energy | Drop (100yd zero) | Wind drift (10mph) |
|---|---|---|---|---|
| Muzzle | 2,350 fps | 1,349 ft-lbs | — | — |
| 100 yards | 2,080 fps | 1,057 ft-lbs | 0" (zero) | 1.0" |
| 200 yards | 1,830 fps | 818 ft-lbs | −4.5" | 4.2" |
| 300 yards | 1,600 fps | 625 ft-lbs | −15.5" | 10.0" |
| 400 yards | 1,400 fps | 479 ft-lbs | −35.0" | 19.0" |
| 500 yards | 1,220 fps | 364 ft-lbs | −65.0" | 32.0" |
125gr supersonic (Hornady Match / Federal Fusion)
| Distance | Velocity | Energy | Drop (100yd zero) | Wind drift (10mph) |
|---|---|---|---|---|
| Muzzle | 2,215 fps | 1,362 ft-lbs | — | — |
| 100 yards | 1,990 fps | 1,100 ft-lbs | 0" (zero) | 1.1" |
| 200 yards | 1,780 fps | 880 ft-lbs | −5.0" | 4.5" |
| 300 yards | 1,590 fps | 702 ft-lbs | −16.5" | 10.8" |
| 400 yards | 1,410 fps | 552 ft-lbs | −36.5" | 20.5" |
Supersonic .300 BLK generates energy comparable to 7.62x39 from a more compact platform. The 110–125gr bullets have better BCs than the 7.62x39's 123gr M43, but the .300 BLK starts slower — limiting its effective range to roughly 300 yards for reliable terminal performance.
Subsonic ballistics
Subsonic loads use heavy bullets (190–220gr) below the speed of sound (~1,125 fps). The purpose is suppressor optimization — no supersonic crack.
220gr subsonic (Federal American Eagle / Hornady Sub-X)
| Distance | Velocity | Energy | Drop (100yd zero) | Wind drift (10mph) |
|---|---|---|---|---|
| Muzzle | 1,010 fps | 498 ft-lbs | — | — |
| 50 yards | 985 fps | 474 ft-lbs | +0.5" | 1.2" |
| 100 yards | 960 fps | 450 ft-lbs | 0" (zero) | 4.8" |
| 150 yards | 938 fps | 430 ft-lbs | −4.0" | 11.0" |
| 200 yards | 917 fps | 411 ft-lbs | −10.5" | 19.8" |
| 300 yards | 878 fps | 377 ft-lbs | −31.0" | 46.0" |
The numbers tell the story: subsonic .300 BLK is a 100–200 yard cartridge. At 200 yards, it drops 10.5" and drifts nearly 20" in a 10 mph wind. Energy at 100 yards (450 ft-lbs) is comparable to a .45 ACP at the muzzle — adequate for soft tissue but limited for hard barriers.
190gr subsonic (Hornady Sub-X)
| Distance | Velocity | Energy | Drop (100yd zero) | Wind drift (10mph) |
|---|---|---|---|---|
| Muzzle | 1,050 fps | 465 ft-lbs | — | — |
| 100 yards | 1,000 fps | 422 ft-lbs | 0" (zero) | 4.5" |
| 200 yards | 955 fps | 385 ft-lbs | −10.0" | 18.5" |
The 190gr Sub-X uses a polymer tip designed to initiate expansion at subsonic velocities — something most hollow points can't do reliably below 1,100 fps. This makes it the best option for subsonic defensive or hunting use where expansion matters.
Barrel length effects
.300 Blackout was designed for short barrels. It burns its powder charge efficiently in 9–10" — unlike 5.56 NATO which needs 16–20" for optimal performance.
Supersonic loads (125gr)
| Barrel length | Velocity | Energy | Velocity vs 16" |
|---|---|---|---|
| 7.5" | 1,920 fps | 1,024 ft-lbs | −295 fps |
| 9" | 2,050 fps | 1,167 ft-lbs | −165 fps |
| 10.5" | 2,120 fps | 1,249 ft-lbs | −95 fps |
| 16" | 2,215 fps | 1,362 ft-lbs | Baseline |
The sweet spot is 9–10.5". Going from 9" to 16" gains only 165 fps (8%) — the powder is mostly burnt by 9". This is why the .300 BLK is the premier short-barreled AR cartridge.
Subsonic loads (220gr)
| Barrel length | Velocity | Energy | Notes |
|---|---|---|---|
| 7.5" | 960 fps | 450 ft-lbs | May not cycle all suppressors reliably |
| 9" | 995 fps | 483 ft-lbs | Reliable cycling with most suppressors |
| 10.5" | 1,005 fps | 493 ft-lbs | Optimal for suppressed subsonic |
| 16" | 1,010 fps | 498 ft-lbs | Negligible gain over 10.5" |
Subsonic loads are even less barrel-length-sensitive. The difference between 9" and 16" is just 15 fps. A 9" .300 BLK with a suppressor is effectively identical in subsonic performance to a 16" setup.
Suppressor performance
.300 Blackout subsonic through a suppressor is one of the quietest centerfire rifle combinations available.
| Configuration | Sound level (approximate) |
|---|---|
| Unsuppressed supersonic | 165+ dB |
| Suppressed supersonic | 136–140 dB (still loud — the bullet's sonic crack is separate from muzzle blast) |
| Unsuppressed subsonic | 160 dB |
| Suppressed subsonic | 125–130 dB (quieter than an unsuppressed .22 LR) |
Suppressed subsonic .300 BLK at 125–130 dB is hearing-safe for occasional shots (though sustained fire still warrants hearing protection). The combination of no muzzle blast and no sonic crack makes it genuinely quiet — action cycling is often the loudest sound.
Critical safety note: Never load supersonic .300 BLK rounds into a magazine intended for subsonic suppressed use without verifying. Accidentally firing a supersonic round through a suppressor won't damage the suppressor, but the supersonic crack defeats the purpose of suppressed shooting and can cause hearing damage if you're not expecting it.
.300 BLK vs 5.56 NATO — ballistic comparison
| Factor | .300 BLK (125gr super) | 5.56 (55gr M193) |
|---|---|---|
| Muzzle velocity (16") | 2,215 fps | 3,050 fps |
| Muzzle energy | 1,362 ft-lbs | 1,135 ft-lbs |
| 300yd drop (100yd zero) | −16.5" | −8.5" |
| 300yd wind drift (10mph) | 10.8" | 8.0" |
| 300yd energy | 702 ft-lbs | 596 ft-lbs |
| Short barrel penalty (9") | −8% velocity | −20% velocity |
| Subsonic option | Yes (purpose-built) | No (defeats the cartridge) |
The .300 BLK hits harder at close range and works dramatically better from short barrels. The 5.56 shoots flatter, drifts less in wind, and is effective to longer range. For a deep comparison: .300 Blackout vs 5.56 for home defense
New to .300 Blackout? If you're considering a .300 BLK build, decide upfront whether you're building for suppressed subsonic use (get a 9–10.5" barrel with a suppressor) or general-purpose use (16" barrel works fine). The cartridge shines brightest as a suppressed subsonic platform — if you don't plan to suppress, 5.56 NATO gives you better range, cheaper ammo, and wider bullet selection.
Related articles
- .300 Blackout vs 5.56 for home defense — Detailed comparison
- Best .300 BLK subsonic ammo — Suppressor-optimized picks
- 7.62x39 vs 5.56 NATO — AK vs AR caliber comparison
- Best ammo for AR-15 — AR-15 ammo picks by use case
- Subsonic vs supersonic ammo — The fundamentals
- 5.56 ballistics chart — M193, M855, and 77gr OTM data
Related caliber pages
- .300 Blackout ammo prices — Current pricing across all retailers
- Cheapest .300 Blackout right now — Lowest observed prices
- .300 Blackout price history — 30-day pricing trends
Sources
- Hornady Ballistic Calculator — Trajectory and energy data
- Advanced Armament Corporation — .300 BLK specification — Original cartridge designer
- Silencer Central — Sound Level Testing — Suppressor dB measurements
- Federal Premium Ballistics Calculator — Velocity and energy reference
- SAAMI Cartridge Specifications — Pressure and dimension standards