How to calculate pellet drop when velocity change
How do calculate the pellet drop when velocity change?
For instance, I zero my rifle at 35 yards, shooting jsb 18.13, when the velocity from 896 fps changes to 883 fps, how do I know how much the pellet drop at 35 yards?
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It took a while to finish my first shot string. Reg. 1530 psi, JSB 18.13 From 220 bar.
Here is 90 shots.
899 900 894 898 896 888 884 883 881
893 896 893 891 890 893 885 888 872
896 890 891 893 888 893 885 884 872
895 896 890 888 894 891 888 887 872
897 888 888 886 888 894 894 892 874
894 888 892 891 890 896 890 884 861
892 894 896 894 889 890 890 887 865
895 895 891 886 891 891 887 881 859
899 891 892 891 885 891 888 881 851
890 892 885 889 889 890 885 884 849
So you are shooting groups of maybe 5 shots and the groups are moving? Anyway, can you post an entire string? The may be a trend going on.
Thanks for the link. Based on the calculation, 896 fps zero at 35 yards, pellet drops 2.94″ and 883 fps same setting, pellet drops by 3.02″. It’s just 0.08″. Here is my problem.
I shot 883 fps at 35 yards, after two or three mags, I realized the POI go up near 1/2″. I went to Chrony it immediantly, the Velocity was 896 fps. Based on the POI drop in the
calculation, I shouldn’t notice any POI change(0.08″) at 35 yards. I don’t know why my POI changed so much.
I’m planning to change all o-rings on Reg. soon.
I always use Chairgun Pro software free from Hawke but a simple ballistics calculator can do the same thing. You need to know the BC of the pellet. Approx. .033 for JSB 18s.
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The problem gone today. I loose a little bit of my tight suppressor. I believe it was a little clipping before when the velocity changed. It’s back to one hole group at 35 yards.