What a range log is for
A range log records where your arrows actually landed — shot by shot, in inches from the point of aim — along with the distance, the equipment and the conditions that produced them. That is a different thing from a training diary. "Shot 60 arrows, felt good" is a feeling. A set of shot coordinates is evidence, and evidence is the only thing that will tell you whether last week's rest adjustment helped or whether you simply had a good day.
The reason to bother is that archery gives terrible feedback in the short term. Groups are noisy, conditions change, and human memory reliably over-weights the most recent session and the most dramatic arrow. A log is how you separate a real change in your equipment or your form from ordinary variation.
Group size: two ways to measure it, one that survives scrutiny
Almost every archer measures groups by extreme spread — the widest gap between two arrows, centre to centre. It is easy, it is traditional, and it is the noisiest statistic in common use.
| Metric | What it measures | How it behaves |
|---|---|---|
| Extreme spread | Distance between the two furthest-apart arrows, centre to centre. | Uses only two shots out of the group no matter how many you shot. Grows as you shoot more arrows, so a 3-arrow group and a 6-arrow group are not comparable. High shot-to-shot variance. |
| Mean radius | Average distance of every arrow from the group's own centre. | Uses every shot. Its expected value does not change with arrow count, and it gets more reliable as you add arrows. The better measure of precision. |
| Group centre offset | Where the group's centre sits relative to the point of aim. | A separate question entirely — this is sight-mark information, not precision information. A tight group in the wrong place is a sighting problem, not a tuning problem. |
The practical consequence is worth stating bluntly: if you compare a 3-arrow group against a 6-arrow group and conclude your gear got worse, you have measured your arrow count, not your bow. Keep arrow count constant when you compare, or use mean radius, which does not care.
Comparing groups across distances
Group size in inches is meaningless across distances until you normalise it. Divide group size by distance and you get an angular measure that compares directly.
| Group | Distance | Inches per yard | Verdict |
|---|---|---|---|
| 2.0" | 20 yd | 0.100 | Baseline |
| 3.0" | 30 yd | 0.100 | Identical precision |
| 4.0" | 40 yd | 0.100 | Identical precision |
| 3.0" | 20 yd | 0.150 | Worse than baseline |
| 4.0" | 60 yd | 0.067 | Better than baseline |
This is also the sharpest diagnostic in the log. If your inches-per-yard number is flat across distances, your precision is scaling normally. If it holds at 20 and 30 but degrades sharply at 50 or 60, something is wrong with arrow flight rather than with your aim — tune, spine consistency, or fletching clearance — because a pure aiming error scales linearly and a flight problem does not.
What to log, beyond where the arrows went
The shots are the data. The context is what makes the data interpretable six months later.
| Field | Why it matters later |
|---|---|
| Distance and arrow count | Without both, no group statistic can be compared to any other. |
| Which bow and which arrows | A session with no setup snapshot is unattributable. This is the single most common gap in hand-written logs. |
| Temperature, wind speed and direction | Wind explains lateral spread; temperature explains velocity, and therefore elevation. |
| Density altitude | Air density changes drag and therefore drop. The reason a sight tape that was perfect in October is off in July. |
| Cold shot vs. warm group | The first arrow of the day is the only one that resembles a hunting shot. Logging it separately is the difference between practising and training. |
| Free-text note | "New string", "moved rest 1/16 right", "target panic on arrows 4–6". The causes of changes live here. |
Reading patterns, not just sizes
The shape of a group carries more diagnostic information than its size. A round group that is simply large is usually a form or a distance problem. A group with a clear axis is usually mechanical, and the axis tells you where to look: horizontal stringing for a right-handed shooter points at grip torque first and cam lean second; vertical stringing points at spine consistency or rest contact; a group that is fine at short range and disproportionately wide at long range points at tune or clearance.
Those mappings are what the Range Log's auto-diagnose feature automates for members, deep-linking from a diagnosed pattern into the specific step of the tuning wizard that addresses it. You can do the same reasoning by hand from a well-kept log; the tool mainly saves you from having to remember which pattern means what.
Discipline beats instrumentation
Two habits do more for a log's usefulness than any feature. First, log the bad sessions. A log containing only your good days will tell you your equipment is excellent and teach you nothing. Second, change one thing at a time. If you swap arrows, move the rest and shoot in a new wind on the same afternoon, the session is uninterpretable no matter how carefully you recorded it.
Sessions, personal bests by distance, streaks and the full history are free. Shot data is stored as coordinates in inches from the point of aim, and the whole log exports to CSV — sessions and individual shots — so the data stays yours. Photos taken with the photo-anchored workflow never leave your device on the free tier, and cloud sync only happens if you choose to sign in. Details on our privacy and data page.
Common questions
What is the best way to measure a group?
Mean radius — the average distance of each arrow from the group's centre — because it uses every shot and does not inflate as you add arrows. Extreme spread is easier to measure but uses only two arrows and grows with arrow count.
Why did my group get bigger when I shot more arrows?
Because extreme spread grows with sample size by definition: more arrows means more chances to throw a wide one, and only the two widest count. Compare groups with the same arrow count, or switch to mean radius.
How do I compare a 20-yard group to a 50-yard group?
Divide group size by distance. A 2-inch group at 20 yards and a 5-inch group at 50 yards are the same precision — 0.10 inches per yard. If that number degrades with distance, suspect arrow flight rather than aim.
Should I log practice sessions that went badly?
Especially those. A log of only your best sessions systematically overstates your equipment and your consistency, and it hides exactly the sessions where a change went wrong.
What does a vertically strung group mean?
Most often spine inconsistency across your arrows or intermittent rest contact, rather than aim. Check whether the pattern persists with a single arrow shot repeatedly — if it does not, the arrows differ from each other.
Why record temperature and air density with a practice session?
Because both change arrow velocity and drag, and therefore drop. A sight tape built in cold, dense air will not match the same bow in hot, thin air, and a log without conditions cannot tell you that is what happened.
Can I get my range data out of The Forge?
Yes. Sessions and individual shots both export to CSV, and that export is the same data the cloud holds if you have chosen to sign in.
The Range Log is part of The Forge by Sparrow Expeditions. Group statistics and data handling are documented on our Methods page. Built by archnerds, for archnerds.