Thread: Testing a conventional approach to load development

For those interested in understanding further whether the testing methodology is valid -


Does shooting 20 round groups allow us to see and measure differences in precision?


Here is an example from a more precise rifle, with 2 loads that DO demonstrate a statistically significant difference in precision.


This is a 20 round group with handloads using the 80gr Targex (incidentally a load randomly selected using the approach described in post 1).

The shooting methodology was - prone, bipod & rear bag, short break between each 5rd group. The mean radius is 0.71cm.

Wind was light (<1ms).





Next we have a 20 round group with Hornady 55gr SP "training ammo".

The shooting methodology was the same, conditions more or less the same.

The mean radius is 1.18cm.





I have photos, for each of these groups, of each of the 4x rd groups that makes up the larger 20rd group. In neither case did the last shots "blow it out"; adding more shots over time simply fills in a better picture as you go.

These groups represent a reasonable picture of the precision of the system with these loads. Even with 20rd the statistical power is limited - in the world of statistics, 20 samples is a small amount when you are trying to detect small differences between means with relatively large standard deviations. However with 20rd groups and the difference in mean between these loads we do have power to detect the difference, and it is a significant difference at the 95% confidence level.






(groups are .9 vs 1.6 MOA)