Hi guys, I need some input and ideas here as I'm close to a loss after troubleshooting everything I know to check. Here's the problem: When I shoot at various ranges my ballistic program calls for x amount of come up based on my inputs. What I've found is that at some distances POI on target may be low (up to 1 MOA), some are spot on and at other distances (farther) POI could be as high as 1 MOA. The same issue is occurring with two different rifles. (Full Custom 300 RUM, 230 Berger at 3,210fps, Vortex Viper PST 6-24 SFP, accuracy is .25 to .5 MOA depending on me.) (Rem 721 300H&H, 215 Berger at 2,670fps, Vortex Diamondback 4-12, accuracy after 300 yards is inside MOA.) I use "Shooter" for my ballisic solutions for both weapons. I have checked Shooter against JBM Ballistics and they match almost perfect which rules out an issue with Shooter. I use a Kestrel 2500 for air density and temperature to input into Shooter. I have confirmed that rifles are still zeroed. I realize this could not be an incorrect velocity issue because I would either by consistently low or high at all distances and that's simple enough to correct for. An incorrect B/C would be easy to fix too. With the RUM I ran the numbers for atmosphere and found the yardage at which I would have exactly 10 MOA of drop. At 672 yards I held over with the 10 MOA bar in my PST and dead centered the 2.5" bull with two shots. Pair was 1.5". This confirmed my input velocity in Shooter was correct. Today I created a MOA grid on freezer paper to be able to physically check scope tracking at 100 yards. MOA lines were Zero, 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, 25, 30, 35 and 40. I did the test several times with each weapon to get an average. The Viper PST averaged within .25 MOA at all distances. The Vortex Diamondback was also within .25 MOA out to 35 MOA of travel. This kind of baffled me because an incorrectly tracking scope would explain this, but the scopes appear to be fine. I borrowed my uncle's new Leica 1000 rangefinder to compare to mine thinking that my rangefinder was lying to me when setting up targets. Nope, they both match within a yard out to 1,100 yards. Both scopes, bases and action screws are tight as they should be. The rear of the guns are always supported well with a rear bag when shooting so as not to cause a vertical POI shift. Any ideas are welcome as this just does not make sense. Thank you!