The Garmin and the AB Quantum app have the exact same engine in them. If they are providing different firing solutions then the inputs in the app and device are different. You will need to go line by line through the app and Garmin to figure out which ones need to be equalized with each other. This means going through all the environment data (Temp, Pressure, Humidity, Latitude), Target Data (Inclination, Azimuth, Wind Speed and Direction), Settings (Aerodynamic Jump (on/off), Spin Drift (on/off), Coriolis (on/off), and profile data (MV Temp Table? Calibrations? Bullet data? Rifle data? Scope data? etc).Something else to note, is that cases of rounding can occur. This is where the app or device displays a whole number (like 40 degrees temperature) but in reality it has an unseen decimal (40.20 degrees) and the devices can do this as well causing 1 to 2 click rounding variations. To account for this always make sure to bump the input up and back down. Say 40 degrees bumped up to 41 then back down to 40. You an also just manually input a whole number. Devices can also have these hidden decimals that account for very small rounding differences.