About this project

What this is

An offline ballistic calculator for Android, plus the knowledge base you are reading. Both exist because the same problem kept coming up: solvers hand out precise-looking numbers without explaining which of their inputs actually decide whether you hit.

The app does the arithmetic. The Academy explains what the arithmetic depends on, the Guides cover driving the app itself, and the Training drills are how you find out whether any of it is working.

Why it is free

Every feature is available to everyone. There is no paid tier, no subscription and no in-app purchase — the billing code was removed from the app rather than left dormant. It is funded by one banner ad at the bottom of the screen.

The reason is practical rather than principled. A ballistic solver with features behind a paywall is a solver whose users are never quite sure whether the answer they got was the good one. Splitting a firing solution into free and paid versions makes the product worse in a way that a banner ad does not.

The solver

A point-mass trajectory integrated with fourth-order Runge-Kutta against the ICAO G1 and G7 drag tables, with separate corrections for atmospherics, wind, spin drift, Coriolis, shot angle, rifle cant and powder temperature.

That is a standard and well-understood model. It is not a proprietary breakthrough and it is not marketed as one. Where commercial solutions differ meaningfully is in offering per-bullet measured drag curves, which this app does not have.

The ammunition data

The catalogue holds 1,600+ factory loads across pistol, rifle, magnum and hunting calibres, assembled from manufacturers' published figures. Each entry records its source.

Published coefficients and velocities are starting points, not measurements of your rifle. Independently measured BCs frequently come in below marketed figures, and a test-barrel velocity is not yours. The honest way to use catalogue data is as an initial estimate you then correct — which is what truing is for.

The same catalogue is published here as a browsable reference, one page per load, with sectional density and form factor derived alongside the published numbers.

Privacy

• No account. Nothing to sign up for, nothing to log in to.
• No sync. Profiles, loads, sessions and cards stay on your device.
• Location is optional and used only for fetching conditions and filling in latitude.
• Advertising uses Google's advertising identifier, with consent requested where regulation requires it.
• Android backup copies app data to your own Google Drive if you leave it enabled.

The full statement is in the privacy policy.

Limits worth knowing

Ballistic output is a prediction computed from the numbers you supply. Four honest caveats:

1. Garbage in, confident garbage out. A catalogue velocity and an estimated scope height produce an answer that looks exactly as authoritative as a good one.
2. Predictions degrade in the transonic region. Past roughly Mach 1.2 the model and the bullet both become less predictable. See transonic.
3. Wind is estimated, not measured. It is the largest error source at distance and no software can fix it for you.
4. Confirm on paper. A solution that has never met a target is a hypothesis, however tidy the interface.

The site

Static HTML generated by a small Node script with no dependencies, hosted on Azure Static Web Apps. Analytics are used only to see which articles are worth expanding, and the cookie banner asks first.

The articles are written to be useful whether or not you install anything. If a page only makes sense as an advertisement, it should not be here.

Corrections

If something on this site is wrong — a number, a formula, a claim about how the app behaves — it is worth reporting through the app's Google Play listing. Technical corrections are welcome and get fixed.

Frequently asked