I think I’ve seen other posts where you’ve said you have to tweak your MV. Don’t mean to come across rude but that is the one thing you should not change (assuming your chronograph is decent, I would check with someone else’s). Your MV should be known and you shouldn’t change that. If you need to tweak anything it should be your BC. That being said inside of 1000 yds if I am not hitting where my calculator says I should it has always been an error in one of my inputs. That’s with Berger and Hornady bullets and the Ballistic AE app. Back to the original posters question I also just downloaded Hornady 4DOF and I have nothing but good to say about it, especially for freeI found that whatever app I use I end up having to tweak the muzzle velocity FPS in order to get the best match in long range groups. Usually start between the 500 yard target to the 900 yard one.