LogBook
A spotting scope on a tripod and a rifle on its bipod at the edge of a ridge, looking out over wide prairie badlands under an evening sky.

The next generation of data book.

What did my rifle do this season?

24 range days, each one kept with the rifle, the load, the lot and the conditions that produced it.

How does your velocity move with temperature?

Muzzle velocity rides the season's weather at +0.9 fps per °F, fitted from 26 °F to 91 °F and never carried past that range. Copy it into Applied Ballistics or a Kestrel.

Did the new lot change anything?

Lot 2 runs +20 fps faster at a common 59 °F. Re-true your solver before you trust last spring's numbers.

Where does the first shot go?

The first round from a cold barrel sits 0.31 MOA high of the warm group on average, each reading measured against that day's group, so a zero change doesn't read as cold bore.

Sample data

Which load should you run?

Average group size by load, sample data Hornady 108gr ELD-M: 0.62 MOA plus or minus 0.05 over 6 groups, the bars being the 90% interval of each average; Berger 109gr LRHT: 0.66 MOA plus or minus 0.05 over 6 groups; Federal 105gr GMM: 0.86 MOA plus or minus 0.08 over 3 groups; Hornady 103gr ELD-X: 0.92 MOA over 2 groups. The top two overlap between 0.61 and 0.67 MOA, so they are too close to call. 0.5 0.7 0.9 Hornady 108gr ELD-M 0.62 ± 0.05 · 6 groups Berger 109gr LRHT 0.66 ± 0.05 · 6 groups Federal 105gr GMM 0.86 ± 0.08 · 3 groups Hornady 103gr ELD-X 0.92 · 2 groups average group size, MOA · bars: 90% interval of the average · rings: each group Average group size by load, sample data Hornady 108gr ELD-M: 0.62 MOA plus or minus 0.05 over 6 groups, the bars being the 90% interval of each average; Berger 109gr LRHT: 0.66 MOA plus or minus 0.05 over 6 groups; Federal 105gr GMM: 0.86 MOA plus or minus 0.08 over 3 groups; Hornady 103gr ELD-X: 0.92 MOA over 2 groups. The top two overlap between 0.61 and 0.67 MOA, so they are too close to call. 0.5 0.7 0.9 Hornady 108gr ELD-M 0.62 ± 0.05 · 6 groups Berger 109gr LRHT 0.66 ± 0.05 · 6 groups Federal 105gr GMM 0.86 ± 0.08 · 3 groups Hornady 103gr ELD-X 0.92 · 2 groups

Too close to call.

0.62 vs 0.66 MOA, after six groups each

The shaded band is where the top two overlap. On this many groups the gap could still be nothing. Whether two loads really differ is decided on the gap between them, not on whether these ranges happen to touch, and getting that wrong sends you to shoot about twice the groups you need.

Sample data

Your chronograph, shot by shot.

Share a session from Garmin ShotView or a LabRadar file and every shot comes in, kept with the session. Leave out a flier and the sample size, average, SD and ES update. Cold bore and clean bore shots are flagged.

Then it reads the string for you. Here, shot 10 sits about 2.7 standard deviations off the other nine. One round doing that is what an ES describes; the rest of the string is tighter than the figures above suggest.

A LogBook session's Muzzle Velocity card, sample data: average 2,529 fps, SD 14.5 fps, ES 43.4 fps over 10 shots, a shot-by-shot chart with each velocity listed, and a note that shot 10 sits about 2.7 standard deviations off the other nine, so the rest of the string is tighter than the ES suggests.

What has your barrel lost?

+7 fpsAs measured

−42 fpsWith temperature taken out, at 56 °F

As measured, this barrel looked faster. The later sessions were shot on warmer days. LogBook fits rounds and temperature together, so the wear shows.

Sample data

How groups get into the record.

A comparison is only as good as the group sizes behind it. Photograph a LogBook target, mark each shot under a zoomed crosshair, and the size in inches and MOA, the mean radius and the correction in clicks for your optic go straight into the session.

Any other target works by marking a known length, and a group measured some other way can simply be typed in.

A LogBook session at 100 yards, sample data: three groups and 15 shots plotted about their own centres, a mean radius of 0.25 MOA, an average extreme spread of 0.53 MOA, and the average adjustment, 0.66 MOA up and 0.50 MOA left, to dial as 3 clicks up and 2 clicks left.

No node.

Run a ladder and LogBook reads it as a trend with its noise. At three shots a step an average wanders about 5 fps on its own, so a flat spot is usually chance.

1 2 3 4 5 6 7 8 charge steps, increasing ±9 fps band
Sample data

A 100-yard zero on a 25-yard range.

Tell LogBook the zero you want and it prints a target with a circle where the group should land. Photograph the group and it gives you the clicks to the circle.

A printed LogBook 25 yard target on a 0.2 mil grid, with an aim cross and a circle just below it labelled 100 YD ZERO.
Example: 5.56, 2,470 fps, G1 0.314, 2.0 in sight height. At 25 yd the group should land 0.91 in low.

Catalogs, from maker data.

  • 986 factory loads
  • 489 suppressors
  • 312 bullets
  • 214 scopes

Your data stays yours.

There is no LogBook account and no server. Your logbook lives on your device and, if you choose, in your own private iCloud, where it syncs to your other devices. Export one firearm as a CSV, or the whole logbook as a zip of spreadsheets with every target photograph. The privacy policy says exactly what is kept and where.

Free to start.

The free logbook has every feature, with unlimited loads, for one firearm and one load work-up. LogBook Pro removes both limits for $19.99 a year (US), billed through your Apple Account. No account. Nothing you log is ever deleted, and you can always export it.

Coming soon to the App Store, for iPhone and iPad.

Make every range day count for the next one.

Tell me when it launches