Recommended reading
Goal of this article: know where to learn the ballistics this guide deliberately does not teach, and which source answers which question.
This application’s manual documents the application. It explains a concept only where the interface would otherwise be unusable, because a primer written here would be a different and much larger book — and it would compete with better ones. This page is what makes that an honest position rather than a gap: everything the guide skips is below, with one line on why each source is worth your time.
Free, and enough to follow this guide
If precision shooting or external ballistics is new to you, these four cover the vocabulary the interface uses:
| Read | For |
|---|---|
| External ballistics | The whole subject in one page: drag, drop, wind deflection, spin drift, the correction terms this application computes |
| Projectile motion | The physics underneath, without air — useful precisely because it shows how much of the problem is air |
| Ballistic coefficient | What a BC actually is — a ratio to a reference projectile, not a property of the bullet. Worth reading before choosing between G1, G7 and a measured table |
| Reticle | Reticle types and subtension, behind the sight-picture view and the MOA/mil choice |
The practical shelf
The books that repay buying, in the order most readers need them:
| Work | Why it is worth your time | Answers questions from |
|---|---|---|
| Litz, Applied Ballistics for Long-Range Shooting | The practical standard. BC, drag models, wind, spin drift and aerodynamic jump explained for shooters rather than engineers — the same terms this application exposes as inputs | Describing the load; atmosphere and wind; choosing a drag model |
| Litz, Ballistic Performance of Rifle Bullets | Measured G1 and G7 BCs and form factors for real projectiles. This is where you get trustworthy numbers to type in, instead of a manufacturer’s optimistic single figure | Describing the load; choosing a drag model; converting a BC between tables |
| Litz, Accuracy and Precision for Long Range Shooting | Hit probability done properly — the WEZ analysis that the hit-probability tool here is a small cousin of, including why group size dominates at some ranges and the wind call at others | Hit probability |
| Vaughn, Rifle Accuracy Facts | Where dispersion actually comes from — barrel, ammunition, bedding, the shooter. It supplies the input the hit-probability tool asks for and cannot compute for you | Hit probability |
| McCoy, Modern Exterior Ballistics | The technical reference behind the engine: point-mass and 6DOF formulations, drag coefficients, and the standard drag families themselves. Heavier going, and the right place to settle an argument about the model | What the model includes; drag models in general |
Nobody needs all five. One Litz title plus the Wikipedia pages above is enough to use this application well; McCoy is for when you want to know why it computes what it computes.
Where this application’s own numbers come from
- The trajectory engine is the BallisticCalculator library — open source, so the integration, the drag tables and the correction terms can be read rather than trusted. If you want to check how a specific number is produced, this is the place.
- Units and conversions come from Gehtsoft.Measurements.
- The aerodynamic-jump and spin-drift formulations follow Litz / Applied Ballistics, which is why the first book above is also the best commentary on those two columns.
- The shipped
.drgtables are radar-derived curves for Lapua projectiles, published by the manufacturer. A measured curve for the projectile in your barrel beats any coefficient you can look up — that argument is the reason this application exists, and it is made at length in What Ballistic Calculator 2 is.
What no book will give you
Two inputs that decide accuracy more than any of the above, and that only your own range work produces:
- Muzzle velocity from your barrel, measured with a chronograph, with its standard deviation. A box figure is a different rifle’s answer.
- Your group size, honestly measured, as the hit-probability tool wants it — a per-axis 1σ figure, not the best three shots you ever fired.
Everything else on this page is reading. These two are shooting.