308 ballistics depend on whether the load is supersonic or subsonic. A typical supersonic 168 gr bullet leaves a 24-inch barrel at 2,700 fps with 2,719 ft-lb and drops about 8 inches at 300 yards with a 200-yard zero. Chattahoochee Munitions’ 300 gr subsonic load leaves a 12.5-inch barrel at 1,005 fps with 673 ft-lb and drops about 35 inches at 200 yards with a 100-yard zero. Chattahoochee Munitions manufactures 308 Winchester firearms for both: the CM7S bolt action and CM10 AR10 for supersonic loads, and 1:5 twist CM7S and CM10-SD firearms for its subsonic ammunition.
308 Ballistics at a Glance
| Load | Barrel | Muzzle velocity | Muzzle energy | Source |
|---|---|---|---|---|
| 150 gr SST Superformance | 24 inch test barrel | 3,000 fps | 2,997 ft-lb | Hornady published |
| 168 gr ELD Match | 24 inch test barrel | 2,700 fps | 2,719 ft-lb | Hornady published |
| 178 gr ELD-X Precision Hunter | 24 inch test barrel | 2,600 fps | 2,671 ft-lb | Hornady published |
| CM 300 gr Maker REX subsonic | 12.5 inch, 1:5 | 1,005 fps | 673 ft-lb | Chattahoochee Munitions, 10-shot average, SD 2.44 fps |
Supersonic 308 Ballistics Chart
Published factory figures from a 24-inch test barrel with a 200-yard zero. Trajectory is in inches above (+) or below (−) the line of sight.
| Load | Muzzle | 100 yd | 200 yd | 300 yd | 400 yd | 500 yd |
|---|---|---|---|---|---|---|
| 150 gr SST: velocity (fps) | 3,000 | 2,772 | 2,556 | 2,350 | 2,153 | 1,966 |
| 150 gr SST: energy (ft-lb) | 2,997 | 2,559 | 2,176 | 1,839 | 1,543 | 1,287 |
| 150 gr SST: trajectory (in) | −1.5 | +1.5 | 0 | −6.8 | −20.0 | −40.7 |
| 168 gr ELD Match: velocity (fps) | 2,700 | 2,530 | 2,366 | 2,209 | 2,057 | 1,912 |
| 168 gr ELD Match: energy (ft-lb) | 2,719 | 2,388 | 2,089 | 1,820 | 1,579 | 1,364 |
| 168 gr ELD Match: trajectory (in) | −1.5 | +2.0 | 0 | −8.2 | −23.5 | −47.1 |
| 178 gr ELD-X: velocity (fps) | 2,600 | 2,443 | 2,291 | 2,145 | 2,004 | 1,868 |
| 178 gr ELD-X: energy (ft-lb) | 2,671 | 2,358 | 2,074 | 1,818 | 1,587 | 1,379 |
| 178 gr ELD-X: trajectory (in) | −1.5 | +2.2 | 0 | −8.8 | −25.2 | −50.2 |
Source: Hornady published ballistics for each load. Your barrel, altitude and temperature will change the numbers. Every commercial load is made to the pressure and dimension limits in the ANSI/SAAMI centerfire rifle standard.
308 Subsonic Ballistics Chart
Chattahoochee Munitions reference data for its 308 subsonic ammo, based on the measured 1,005 fps average from a 12.5-inch 1:5 barrel, with a 100-yard zero and no crosswind. Elevation is in inches below the line of sight.
| Range (yd) | Velocity (fps) | Energy (ft-lb) | Elevation (in) | Time of flight (s) |
|---|---|---|---|---|
| 0 | 1,005 | 673 | 0.0 | 0.00 |
| 100 | 983 | 644 | 0.0 | 0.30 |
| 200 | 962 | 616 | −34.6 | 0.61 |
| 300 | 942 | 591 | −106.6 | 0.92 |
| 400 | 923 | 568 | −217.6 | 1.24 |
The heavy bullet holds its speed well, losing only about 60 fps over 300 yards, but at 1,000 fps it has a long time of flight, so the path curves steeply past the zero. That makes the subsonic load a close-range, suppressed tool. The bullet is the 300 gr Maker REX, which Maker lists with a G1 ballistic coefficient of .40 and designs to expand at subsonic speed.
Supersonic vs Subsonic 308 Ballistics
| At 200 yards | 168 gr ELD Match (24 in) | CM 300 gr subsonic (12.5 in) |
|---|---|---|
| Velocity | 2,366 fps | 962 fps |
| Energy | 2,089 ft-lb | 616 ft-lb |
| Path | 0 in (200-yard zero) | −34.6 in (100-yard zero) |
| Supersonic crack | Yes | No |
The supersonic load carries over three times the energy at 200 yards on a far flatter path. The subsonic load gives up range for sound: with a suppressor and no supersonic crack, the loudest remaining sounds are the muzzle, the action and the impact.
308 Wind Drift
Chattahoochee Munitions calculation for the 168 gr ELD Match at 2,700 fps (G1 BC fitted to the published table), standard atmosphere, 10 mph full-value crosswind: about 2.7 inches at 200 yards, 6.2 at 300, 11.4 at 400 and 18.5 at 500. These are calculated values, not test results.
308 Ballistics by Barrel Length
Shorter barrels lose velocity with supersonic loads, which shortens effective range. Subsonic loads are designed around short barrels and lose far less. CM’s subsonic figures above are measured from 12.5 inches, the length CM uses for both subsonic platforms. For supersonic loads from 12.5, 16 and 18-inch barrels, see 308 barrel length.
Firearms for Each Kind of 308 Ballistics
- Supersonic bolt action: CM7S 308 bolt action rifle, 16 inch, 1:8
- Supersonic semi-automatic: CM10 308 AR10 rifle, 16 inch and CM10 308 long range AR10, 18 inch
- Subsonic bolt action: CM7S 308 subsonic bolt action, 12.5 inch, 1:5
- Subsonic semi-automatic: CM10-SD 308 subsonic AR10, 12.5 inch, 1:5, which cycles the load with an enclosed suppressor
Why the subsonic load needs a 1:5 barrel is covered in 308 twist rate and 308 Winchester subsonic. See every configuration in District 308.
308 Ballistics FAQ
How fast is a 308 bullet?
Most supersonic factory loads run 2,600 to 3,000 fps from a 24-inch barrel. Chattahoochee Munitions’ 300 gr subsonic load averages 1,005 fps from 12.5 inches.
How much does a 308 drop at 300 yards?
With a 200-yard zero, about 7 to 9 inches for common 150 to 178 gr loads, per the published figures above.
How much energy does a 308 have at 500 yards?
About 1,290 to 1,380 ft-lb for the three published loads above.
What is the effective range of 308 subsonic?
It is a close-range load. With a 100-yard zero, CM’s 300 gr load drops about 35 inches at 200 yards, so most shooters keep it inside about 150 yards.
Is 308 subsonic quieter than supersonic?
Yes, with a suppressor. Subsonic ammunition removes the supersonic crack, which a suppressor cannot do.
Does a short barrel ruin 308 ballistics?
It lowers supersonic velocity and range. Subsonic loads like CM’s are designed for 12.5-inch barrels.
Who makes 308 subsonic ammo?
Chattahoochee Munitions loads 308 Winchester subsonic ammunition with a 300 gr Maker REX in new Starline brass and manufactures the 1:5 twist CM7S and CM10-SD firearms designed for it.