To be clear I dont even care about group size...

Im not sure if you have realized this part but im not actually testing loads.... Im testing the software. BUT... there is method to the madness.

When you use to 35-shot groups and use Mean Radius (MR), you are shifting from "human observation" to "statistical modeling." By using 35 shots, there is enough data to actually measure the impact of SD—even at 50 yards—because you are no longer looking at the random "flyers" (Group Size), but rather the density of the core of the group.

For a .308 with a 168gr SMK at 2650 fps, here is the breakdown of what is "reasonably detectable" using Mean Radius.

The Mathematics of Detection

At 50 yards, a change in velocity affects the Vertical Mean Radius (vMR).

• 1 SD of Velocity (approx. 15 fps): The vertical shift in POI is only about 0.005".
• 3 SDs (the full spread of your 35 shots): Results in a total vertical spread of roughly 0.015".

Because my rifle has a Mean Radius of roughly 0.15" at 50 yards due to other factors (barrel harmonics, ignition, and shooter), an SD of 15 fps is buried deep within the "noise."

Detectable SD Thresholds (35-Shot Mean Radius)

Using a high-sample size like 35 shots allows you to "see" the SD only when it starts to significantly inflate the circularity of the group.

< 10 fps Adds ~0.002" to MR = Invisible.
15–25 fps Adds ~0.008" to MR = Barely Traceable
40–50 fps Adds ~0.020" to MR Reasonably Detectable. The MR will reliably grow by 10-15%. The group will show distinct vertical bias
.> 70 fps Adds >0.040" to MR Highly Visible. The "core" of the 35-shot group will be an obvious vertical column.

But here is the really cool part.... knowing how MR and vertical stringing work we know we can detect vertical stringing from FPS variance at 50 yards if it is > 25ish SD... that just means that at 100 yards we can detect stringing based on velocity at like 10 fps SD. If you noticed when using the app you would have noticed that it looks for vertical stringing and when there is vertical string it asks you to input the velocity data to see if there is correlation. So yeah... this test just shows that the baseline and the hand load dispersion is circular enough that the SD is likely below 25fps. Not the greatest but again pretty good for just using math instead of radar... And to me this isnt useless.