How-to · Updated October 2, 2026
Should you use a G1 or G7 ballistic coefficient?
Direct answer
Use the G7 number with a G7 drag model, and the G1 number with a G1 model. A 6.5 Creedmoor 143 gr ELD-X is G1 0.623 or G7 0.314. Those two matched settings agree. Typing 0.623 into a G7 model predicts −235.4 in at 1,000 yards instead of −309.9 in.
Same bullet, three calculator settings
2,700 fps, 200-yard zero, 1.5 in sight height, sea level, 59 °F, no wind. Path is inches from the line of sight.
| Range | G7 0.314 | G1 0.623 | G1 number in the G7 model |
|---|---|---|---|
| 300 yd | −7.9 in | −7.9 in | −7.1 in |
| 500 yd | −44.6 in | −44.7 in | −38.6 in |
| 1,000 yd | −309.9 in | −309.9 in | −235.4 in |
At 500 yards the matched models are 2,018 fps (G7) and 2,016 fps (G1). The mismatched G7 run is still at 2,342 fps because it was given too high a coefficient.
The BC also changes with speed
Hornady’s advertised figure is the Mach 2.25 BC. For the 6.5 mm 143 gr ELD-X the three bands are:
| Speed | G1 | G7 |
|---|---|---|
| Mach 2.25 | 0.623 | 0.314 |
| Mach 2.0 | 0.604 | 0.303 |
| Mach 1.75 | 0.584 | 0.294 |
This calculator uses one BC for the whole flight, the Mach 2.25 number on the factory-load list. A Doppler solver such as Hornady 4DOF steps the drag curve instead.
Loads that stay on G1
These factory loads in the calculator have a G1 BC and no G7 BC: .30-06 Springfield 150 gr SST (G1 0.415); .223 Rem 55 gr V-MAX (G1 0.255); .30-30 Win 160 gr FTX (G1 0.33). Keep the drag model on G1 for those.
Limits
- G7 is a better shape match for a long boat-tail. It is not a larger BC. 0.314 G7 is not “worse” than 0.623 G1.
- A point-mass trajectory is not a substitute for a confirmed zero. Velocity from your barrel changes the path.
- This calculator is independent of Hornady. The BCs are the figures Hornady publishes for these bullets.
Use the calculator
Turn the path into a scope click: how to convert bullet drop to MOA. Compare loads in the Hornady ballistics calculator.