300 Blackout vs 308 is a choice between a small, short-barreled .30 caliber and a full-power one. Both fire .308-inch bullets. The 300 Blackout fits an AR15 and is designed around subsonic loads from 8 to 10.5-inch barrels. The 308 Winchester needs an AR10 or a short-action bolt gun and carries about twice the supersonic energy to much longer range, and with heavy bullets it also runs subsonic. Chattahoochee Munitions manufactures firearms in both: the CM15 and CM7S in 300 Blackout, and the CM10 AR10 and CM7S in 308 Winchester, plus its own 308 subsonic ammunition.
300 Blackout vs 308 at a Glance
| 300 Blackout | 308 Winchester | |
|---|---|---|
| Bullet diameter | .308 inch | .308 inch |
| Parent case | .223 Remington | Its own (7.62 NATO family) |
| Case length | 1.368 inch | 2.015 inch |
| SAAMI maximum average pressure | 55,000 psi | 62,000 psi |
| Platform | AR15 or short bolt action | AR10 or short-action bolt action |
| Typical subsonic bullet | 190 to 245 gr | Up to 300 gr |
| Typical supersonic bullet | 110 to 150 gr at 2,000 to 2,400 fps | 150 to 180 gr at 2,600 to 2,800 fps |
| Full powder burn | About 9 to 10.5 inches | Needs a longer barrel |
Dimensions and pressures follow the ANSI/SAAMI centerfire rifle standard.
300 Blackout vs 308 Subsonic
Subsonic is where most 300 Blackout owners start, and it is a closer contest than the supersonic numbers suggest. Both cartridges are held under about 1,050 fps, so the difference is bullet weight. Both loads here use solid copper expanding bullets from Maker Bullets. Black Butterfly’s 300 Blackout 200 gr Maker Buzz Saw subsonic averages 1,025 fps from a 16-inch barrel, about 467 ft-lb. Chattahoochee Munitions’ 308 Winchester 300 gr MAKER REX expanding subsonic averages 1,005 fps and 673 ft-lb from a 12.5-inch barrel, about 44 percent more energy at the muzzle, and it needs a 1:5 twist. The 308 asks for an AR10 or a short action to get it. See 308 Winchester subsonic and 300 Blackout subsonic.
| Range | 300 BLK 200 gr Buzz Saw subsonic: energy / drop | 308 Win 300 gr subsonic: energy / drop |
|---|---|---|
| Muzzle | 467 ft-lb | 673 ft-lb |
| 100 yd | 416 ft-lb / 0 | 644 ft-lb / 0 |
| 200 yd | 376 ft-lb / -35.6 in | 616 ft-lb / -34.6 in |
| 300 yd | 344 ft-lb / -112.2 in | 591 ft-lb / -106.6 in |
The 308 values are from Chattahoochee Munitions’ published table for that load. The 300 Blackout values are Chattahoochee Munitions calculations from Black Butterfly’s published 1,025 fps, with a 100-yard zero and standard atmosphere. Maker does not publish a ballistic coefficient for the 200 gr bullet, so the calculation uses an estimate of 0.36 G1, scaled from Maker’s published figure for its 220 gr REX. Both drop steeply past 150 yards, as every subsonic load does.
300 Blackout vs 308 Supersonic Ballistics
The table compares Hornady’s 110 gr V-MAX in 300 Blackout (2,375 fps, 16-inch test barrel) with Hornady’s 168 gr ELD Match in 308 Winchester (2,700 fps, 24-inch test barrel). Downrange values are Chattahoochee Munitions calculations with a 200-yard zero, standard atmosphere and a 10 mph full-value crosswind.
| Range | 300 BLK 110 gr: energy / drop / wind | 308 Win 168 gr: energy / drop / wind |
|---|---|---|
| Muzzle | 1,378 ft-lb | 2,719 ft-lb |
| 100 yd | 1,071 ft-lb / +3.2 in / 1.4 in | 2,388 ft-lb / +2.0 in / 0.6 in |
| 200 yd | 821 ft-lb / 0 / 6.2 in | 2,089 ft-lb / 0 / 2.7 in |
| 300 yd | 622 ft-lb / -13.7 in / 14.8 in | 1,820 ft-lb / -8.2 in / 6.2 in |
| 400 yd | 470 ft-lb / -41.0 in / 28.1 in | 1,579 ft-lb / -23.5 in / 11.4 in |
Supersonic, the 308 carries about three times the energy at 300 yards and drifts less than half as far. Chattahoochee Munitions designs its 1:5 barrels for subsonic loads; for supersonic ammunition it offers the 16-inch CM15 with a 1:7 twist. In 300 Blackout vs 308 terms, the 308 is the long-range and large-game cartridge. See 300 Blackout ballistics.
Size, Weight and Barrel Length
The 300 Blackout’s advantage is the firearm around it. It runs in an AR15 with a standard bolt and magazines, and it gives up little velocity in a 10.5-inch barrel. The 308 needs a larger receiver and a heavier bolt carrier, and it loses more velocity as the barrel gets shorter. For a compact suppressed firearm the 300 Blackout is lighter and shorter. For a firearm that reaches out, the 308 is worth the size.
300 Blackout vs 308 Recoil and Ammunition
The 300 Blackout recoils much less. Supersonic 308 recoils noticeably in a light firearm, and suppressed subsonic 308 is mild. Both have wide ammunition choice, and the 308 has more long-range and big-game loads. Chattahoochee Munitions loads 308 subsonic ammunition and does not load 300 Blackout; Black Butterfly Ammunition offers 300 Blackout subsonic and supersonic loads.
300 Blackout vs 308 for Hunting
- Hogs and deer inside about 100 yards, suppressed: both work subsonic with expanding bullets. The 308 subsonic carries more energy.
- Deer and hogs to 200 yards: supersonic 300 Blackout from the 16-inch, 1:7 twist CM15 works with an expanding bullet.
- Elk and longer shots: 308 Winchester.
- Bear: choose a heavier cartridge. Chattahoochee Munitions recommends the 375 Raptor or the 458 SOCOM XL.
See 300 Blackout hunting.
300 Blackout vs 308: Which Should You Choose?
Choose 300 Blackout for a light AR15-size suppressed firearm, short barrels and mild recoil inside about 200 yards. Choose 308 Winchester for more subsonic energy from a bolt gun or AR10, and for supersonic hunting and target shooting past 300 yards.
- 300 Blackout: CM15 300 Blackout AR15 SBR, 10.5-inch, CM7S suppressed 300 Blackout hunting rifle, 10-inch, and every configuration in Sector 300.
- 308 Winchester: CM10-SD 308 subsonic AR10, 12.5-inch, CM7S 308 subsonic bolt action, 12.5-inch, and District 308.
300 Blackout vs 308 FAQ
Is 300 Blackout the same bullet as 308?
The diameter is the same, .308 inch. The 300 Blackout case is much smaller, so it fires lighter bullets supersonic and is designed for heavy bullets subsonic.
Is 308 better than 300 Blackout?
For range and energy, yes. For a light, short suppressed AR15, the 300 Blackout fits better.
Is 308 subsonic stronger than 300 Blackout subsonic?
Yes. A 300 gr 308 subsonic at about 1,005 fps carries about 670 ft-lb against about 470 ft-lb for a 200 gr 300 Blackout subsonic such as the Maker Buzz Saw.
Can a 300 Blackout AR15 shoot 308?
No. The 308 case is far longer and needs an AR10 or a short-action bolt gun.
Which recoils less, 300 Blackout or 308?
The 300 Blackout, by a wide margin with supersonic loads.
Is 300 Blackout a 308 for an AR15?
Only in bullet diameter. Supersonic 300 Blackout carries about half the 308’s muzzle energy and much less at range.
Who makes 300 Blackout and 308 rifles?
Chattahoochee Munitions manufactures 300 Blackout firearms on the CM15 AR15 and CM7S bolt action, and 308 Winchester firearms on the CM10 AR10, including the CM10-SD 308 subsonic, and on the CM7S bolt action.