Powder grades & calibration
What Estimated, Provisional, and Calibrated mean — and why measured beats fitted beats estimated.
Every powder’s burn model carries a grade — how much you should trust predictions made with it.
The three grades
- Estimated: derived from the powder’s position on the relative burn-rate chart. Wide intervals on purpose.
- Provisional: fitted to published load data. Better, but published data is someone else’s barrel.
- Calibrated: fitted to your chronograph data in your barrel — the only grade that has seen your firearm.
Calibrating
Log a string against a load, then Calibrate: the model refits the powder’s burn rate to your measured velocity, records the string’s temperature and SD, and future predictions for that barrel + powder pair carry the calibration.
Bundled catalog data never exceeds Provisional; Calibrated is reserved for your own measurements. That ordering is the point: measured beats fitted beats estimated.