Guide

JBM Ballistics Is Gone. Here's the Replacement, Page by Page.

For about fifteen years, JBM Ballistics was the shooter's default: a free web page that ran a standard point-mass trajectory over the published G1 and G7 drag curves and printed the card you taped to your stock. In 2026 the calculators came down. The homepage is an app page now, and a decade and a half of forum posts, articles, and printed cards point at a tool that no longer answers.

What JBM actually did (and why it's rebuildable)

JBM never owned its math. It ran a standard point-mass model over the standard G1/G7 drag functions — tabulated in McCoy's Modern Exterior Ballistics and published for anyone to use. The curves didn't retire with the website. What retired was the web-native, no-install, printable implementation: the trajectory page, the range cards, the trajectory cards with their temperature × altitude matrix, the μCards, maximum range, recoil, energy, power factor, BC conversion, and the Miller stability page.

The honest state of the replacements

The factory solvers are excellent and free — Hornady's 4DOF and Sierra/Barnes TrueData use Doppler-measured drag for their own bullets and beat any standard-model solver for those bullets. Berger's calculator is a clean G7 tool. If all you need is a firing solution for a factory bullet, use them; we say so on our own calculator pages. Applied Ballistics is the professional reference.

What none of them rebuild is JBM as a website: brand-neutral standard-model calculators that take any bullet, print a card, and sit one click from the record of what you actually loaded and measured. The paid log tools that exist are desktop installs or subscriptions. That combination — free web calculators feeding a one-time-purchase web log — is the hole TruingLog was built into.

Rebuilding your JBM cards

• Trajectory — the trajectory calculator runs the same standard models, with a 179-bullet library of manufacturer-published BCs.
• Range / trajectory cards — the range card and trajectory card generators reproduce the card formats, including the temperature × altitude matrix.
• μCards — the compact card, with wind-only and constant-drop variants.
• Utilities — recoil, energy, power factor, BC conversion, stability, maximum range.

How we know the numbers are right

Before a single page shipped, the solver was gated against published known-answers: Hornady's factory table for the 140 gr ELD Match (agreement within ~0.6 inches and ~25 fps at 500 yards on both drag models), Applied Ballistics' published solver comparison at 1,000 meters (within 0.3 mil), Berger's published dope via Lapua, Sierra's worked examples, and the exact wind-drift lag rule. Where a published source disagrees with the standard models — Hornady's Doppler-generated ELD-X tables read about 6–8% more drop at 500 yards — we publish the deviation instead of tuning it away. The full arbitration is in the open: it's the same honesty standard we apply to chronograph SDs.

JBM's real legacy was trust earned one printed card at a time. That's the bar.