Short answer: pick 300 Blackout if you want more energy, more effective range and the best suppressed performance; pick 10mm if you want a pistol-caliber carbine that is simple, short and can share ammo (and sometimes magazines) with a Glock 20 or other 10mm handgun. From a 16" barrel, a supersonic 110 gr 300 BLK load carries about 1,350 ft-lbs at the muzzle versus roughly 850 ft-lbs for a full-power 180 gr 10mm load.
Quick comparison
| 10mm Auto | 300 Blackout | |
|---|---|---|
| Typical bullet | 155–200 gr pistol bullet | 110–125 gr supersonic, 190–220 gr subsonic |
| Velocity, 16" barrel | ~1,450–1,750 fps (180 gr / 150 gr) | ~2,300 fps (110 gr) |
| Muzzle energy, 16" barrel | ~850–1,000 ft-lbs | ~1,350 ft-lbs |
| Realistic range | ~100–150 yd | ~200–300 yd (supersonic) |
| Suppressed | Supersonic with most loads | Excellent with subsonic loads |
| Action in an AR | Usually blowback (pistol-caliber) | Direct impingement, standard AR-15 BCG |
| Magazines | Glock 20 pattern or dedicated | Standard AR-15 magazines |
| Recoil | Mild in a carbine | Mild, slightly more muzzle blast |
Velocity figures are typical published numbers; your results depend on load and barrel length.
Ballistics and terminal performance
10mm is the hottest common pistol cartridge. In a 5" handgun a 180 gr load runs about 1,250–1,300 fps; a 16" carbine adds roughly 200 fps. That makes a 10mm carbine one of the most powerful pistol-caliber options for defense inside 100 yards.
300 Blackout is a rifle cartridge built on the 5.56 case. Supersonic 110–125 gr bullets leave a 16" barrel at around 2,300 fps and still carry rifle-level energy at 200 yards. From a short 9" barrel, 300 BLK keeps more of its velocity than most rifle rounds, which is why it dominates the micro AR pistol category.
Barrel length and short pistols
Short barrels favor both rounds. 300 BLK was designed to burn its powder in about 9", so a 5"–9" AR pistol gives up less than a 5.56 would. 10mm also burns most of its powder quickly, so a 5.5"–8" 10mm AR pistol stays compact without much loss.
Suppressor use
This is where 300 Blackout pulls ahead. Subsonic 190–220 gr loads run about 1,000 fps, below the speed of sound, so a suppressed 300 BLK is very quiet and still cycles a standard AR. Most 10mm loads are supersonic out of a carbine barrel, so you get a supersonic crack unless you choose a heavy subsonic load. See our guide to the best suppressor for a 5" 300 BLK pistol.
Platform: how each one runs in an AR
300 BLK uses a normal AR-15 lower, standard magazines and a standard bolt carrier group; only the barrel changes. 10mm ARs are pistol-caliber carbines: most run blowback with a heavier buffer and use Glock-pattern magazines, so a 10mm carbine can share magazines with a Glock 20. Browse our blowback PCC line for 10mm and other pistol calibers.
Ammo cost and availability
Both are widely available. Practice-grade 10mm and 300 BLK usually sit in a similar price range, both well above 9mm and 5.56. Check current prices before you decide, since 10mm and subsonic 300 BLK prices vary the most.
Which should you buy?
- Home defense / truck gun inside 100 yards: either works; 10mm if you already carry a 10mm handgun.
- Hunting deer or hogs to 150–200 yards: 300 Blackout supersonic.
- Suppressed shooting: 300 Blackout with subsonic ammo.
- Simplest pistol-caliber carbine that shares ammo with your sidearm: 10mm.
Still choosing between pistol calibers? Read 10mm ARP vs 9mm ARP.
FAQ
Is 10mm more powerful than 300 Blackout?
No. From the same barrel length, supersonic 300 Blackout has more velocity and energy. 10mm is the more powerful pistol cartridge, not the more powerful round overall.
Is 300 Blackout better for a suppressor than 10mm?
Yes. 300 BLK subsonic loads are designed for suppressors and cycle a standard AR; most 10mm carbine loads are supersonic.
Can a 10mm AR use Glock magazines?
Many 10mm AR carbines and pistols are built for Glock 20 pattern magazines. Check each listing for its magazine type.
Which is better for deer hunting?
300 Blackout with a supersonic hunting bullet, out to about 150–200 yards. Check your state's hunting rules for caliber requirements.
Which has less recoil?
Both are mild in an AR. 300 BLK can have more muzzle blast from very short barrels.
Sources: Rifle Magazine, Ruger LC Carbine 10mm; Pro Armory, 300 Blackout ballistics.
