Applied Ballistics is one of my favorite for external ballistics. It lets you save multiple firearms with custom properties and multiple types of ammo for each. It is very customize able and has always given me spot on data. It can also use your GPS and calculate much of the atmospheric data by itself.
For a shot timer I use Splits. It does not do well with suppressors, but has helped me greatly when training. One day I will invest in a real shot timer.
Reload Logbook is great for storing all of your custom load data. It backs it up to the cloud so it is great if you have multiple devices.
“If a man does his best, what else is there?”
– General George Patton Jr