Thread: What's the Deal?

I did some shooting the other weekend with my .260 Rem and 140gr A-Max combo. From 9 measured shots through the chrony I got an average of 2644fps. Using Litz measured G7 BC of .299 for the A-Max Leathel entered all the necessary digits in to his Shooter app for 500m and I think it said 3.2 mils up. I shot it at that and I saw I was about a mil low. I adjusted up .8 mil to 4 mil, shot it again and it was bang on. We had a play with the input speed and to get that calculation it had to be set at 2500fps. WTF? We moved back to 650m and input everything the same as before but adjusted the speed for 2500fps, it said 6.2 mil up. Adjusted and shot it, and it was bang on. I have since entered this into JBM as well and got the same results with the muzzle velocity set at 2500fps. Any ideas what might be going on?

Thanks