Do you want to play with an app a few times for kicks, or do you want to have a serious tool for regular long-range shooting in changing conditions with multiple weapons/ammo?
If the latter I highly recommend Applied Ballistics developed by Bryan Litz. It is by far the most complete, most flexible, most awesome ballistics app available. Some of the killer features include ability to save a library of specific weapons and ammo. You can back it all up to the cloud and restore with a click of a button. I backed up, bought a new phone, the restored all my data with a few clicks. Awesome. You can generate a custom table and then email it to yourself, or to your buddy. After you create a specific profile for a weapon/ammo combo if your POI is off you can enter the POI error at the specific range and it will do a calibration correction across your whole table. Unlike many apps it corrects for all variables including angle of fire and Coriolis based on Latitude and direction of fire. It can even pull barometric pressure from the nearest online weather station based on your GPS coordinates. All of these functions can be enabled/disabled as needed. Cost? Well it's the most I've ever paid for an "app" but I am 100% satisfied.