When I first started getting into long range shooting and soon after, practical long range field matches, there was an overwhelming amount of information/opinions on everything long range related. There was so much to learn. What gun, optic, ammunition etc etc.
One of the topics was how to gather ones "dope" or "data" and than apply that to changing weather conditions, locations, elevations, temps and whole host of other variables. There were people suggesting using information from Sierra, JBM, or shooting at each specific location/altitude etc to gather all the info. This was the best method, but not very practical or feasible. It was as also more difficult to adjust on the fly. If you happen to have forgotten your data cards or needed to make an adjustment to your dope, it was a pain.
I had a buddy that was new to long range shooting as well and we had both heard about a new app in the apple store called Ballistic. http://ballisticapp.com/ So we both decided to purchase it and give it a try. Once we learned to use the app, which was pretty easy to operate. I was a believer. You input all your information into it for your given load for a particular rifle. From there I could adjust the DA (Density Altitude) and print out cards for the various DA's I was gonna need when I traveled to matches. It was so simple to operate and very convenient to always have your ballistic software with you. If your gun picked up speed or slowed down while your shooting the match, Adjustments could quickly and easily be made in the hotel room in the evening, with new data cards printed out and ready for the next day.
The data we got from Ballistic was always very on point for us. One of the big things for me is having faith in your equipment, including your ballistic software. If you have confidence in your equipment and in your dope, you will be a better shooter.
Fast forward to today, my buddy (now a team AA shooter Tim. M) and I still use the Ballistic app. It has proven itself to be very reliable and it is still just as easy to use now as it was than. They continue to add more features to the app while still maintaining the easy to use interface.
We here at AA recommend you give Ballistic a look!