Shooter is a ballistic app. If you know the muzzle velocity of your rounds, the coefficient of drag, temperature, scope height, elevation, angle... the software will calculate your "comeups" or scope elevation adjustments for different distances.
A similar app (free) is Strelok.
Once you have a suitable weapon, do not skimp on the scope, base, or rings. It is a weapon "system" only as capable as its weakest link.