Range Report Chronograph Testing

ARx3

Private
Minuteman
Jul 6, 2019
54
241
69
Kansas
I was able to get out Friday for a quick chronograph test on my wife's 6.5 PRC. Factory Hornady 147 ELD-M out on her 24" Krieger barrel Averaged 2869.5 fps with an ES of 23.6 fps and SD of 9.9 fps. A little slower than the 2910 fps on the box. The weather was great,I only wish that I had had more time to test more loads.
Chrongraph Testing 6.5 PRC (2).jpg
 
What is the general consensus here on the number of rounds in a string and the number of strings that should be shot in order determine a particular load's potential ?
 
Statistically, at least 30. That is not always practical. There is an advertised error rate for your chronograph so that is a factor as well though not very material. Most run with 10 shots to reach an 80% confidence. Then we true up down range.
 
Example, if your chronograph is accurate to 1% than your results with just those five shots are close to that margin of error. 2870/2910
 
Thanks for the information. I'm new to the precision rifle game but have been use to chronographing pistol loads to determine power factor and accuracy. I do usually shoot 10 round multiple strings to confirm my pistol ammo that I use in competition . I have the Shooter App on my phone and have found it really useful. I probably won't ever compete in any long range precision events but I like the idea of being able to compare my loads to factory ammo. I also like to find the best load I can for our rifles fully realizing that I'm the weak link behind the trigger. I have been handloading since 1978 and my chronograph is a older Pact Professional Model that I have had for years.