This web application is a comprehensive tool designed for shooting enthusiasts, competitive marksmen, and handloaders. Our goal is to provide a single, powerful platform to manage every aspect of your shooting hobby, from the components on your reloading bench to the final analysis of your performance on the range.
For the best experience, we recommend following this workflow:
When evaluating the precision of a load, it's tempting to rely on small, 3 or 5-shot groups. They are quick to shoot and easy to measure. However, the results from such small sample sizes can often be misleading. A tight 3-shot group might be a statistical fluke rather than a true representation of your load's potential, just as a surprisingly wide group might be the result of a single random flyer.
The power of statistical analysis, and a core principle of this application, lies in using larger data sets. As you increase the number of shots in your sample—from 5 to 10, and ideally to 20 or 30—the calculated metrics like Mean Radius become far more reliable. These larger groups smooth out the randomness of individual shots, giving you a much clearer picture of the load's true capabilities.
This becomes critically important when comparing two different loads. Is your new handload really more precise than the old one? Comparing two 5-shot groups might not provide a definitive answer, as the difference you see could easily be due to chance. The more data you collect, the more confident you can be in your conclusions.
All your data is stored securely and privately in your local browser database. Nothing is uploaded to a server, ensuring you have full control over your information and can even use the application offline.
| Nickname | Cartridge | Barrel | Twist | Actions |
|---|
Impact data will appear here once you mark points and set a scale.
Select one or more sessions and click analyze.
Mean Radius: The average distance of all shots from the geometric center (mean point of impact) of the group. A smaller value indicates better precision. This is the primary metric used for ranking.
CI for Mean Radius (95%): This provides a likely range for the true Mean Radius of your load, calculated using bootstrapping. Because you are using a sample of shots, the measured Mean Radius has some uncertainty. The color-coded text indicates the level of confidence based on the width of this interval relative to the measured value. A narrow interval (High confidence) gives you high confidence that your measurement is close to the true value. A wide interval (Low confidence) indicates high uncertainty, usually due to a small number of shots.
SD (Horizontal/Vertical): The Standard Deviation of shot placement on each axis. Measures the consistency of shots along that axis.
Velocity SD (Standard Deviation): A measure of the consistency of the muzzle velocity. A lower SD indicates more consistent ammunition.
Vertical Stringing: The analysis automatically checks if the vertical spread (SD) of the group is significantly larger than the horizontal spread (specifically, if Vertical SD is > 1.5x Horizontal SD). If detected, it suggests a potential issue, often related to inconsistent muzzle velocity.
Velocity Correlation (R²): If vertical stringing is detected and velocity data is available (for 3+ shots), an R-squared (R²) value is calculated. This value, from 0% to 100%, indicates how much of the vertical shot placement can be explained by changes in velocity. A high R² value (e.g., > 40%) strongly suggests that inconsistent muzzle velocity is a primary cause of the vertical spread.
| Name | Types | Actions |
|---|
| Imperial | Metric | Actions |
|---|
| Name | Diameter | OAL | Actions |
|---|
Select a table to view its contents.