Originally Posted by pills
after getting my load right (51.5g H4831sc/ Lapua Brass/ 140g Berger VLD hunting @ 2750fps) in my Cooper 24" 1 in 8 barrel. I am making my drop card, using shooter app. and JBM program. Both gave me the same values . With a 200 yrd zero they give me a 300 yrd drop of 2.4moa (10 clicks) Vortex 4-16 PST on MOA. Problem is when I shoot this I end up 2.5" low at 300. I shot two 3 shot groups then switched to 3 MOA (12 clicks) and was shooting dead center. groups were all very good for me .6 to 1.75" at 300. Any ideas on the difference in the programs and actual results?
At sea level
I just quickly ran the data you provided above in QuickLOAD and it spit out a velocity of 2721. With a 200 yard zero the come up for 300 is 2.39 MOA so your data is close
So if I was getting what you are the first thing I would look at is the zero. It has to be absolutely perfect for the come up data to be correct. In your program run it with a zero of 195 yards and see what you get. In QL that come up would be 3.09 MOA. So if you are zeroed just a tad low at 200 like a 1/4" (a guess) that would account for what you are seeing. Something to check.