Aside from hardware factors, I recommend the 'Shooter' ballistic app for your phone, as well as the 'Rigid' level app. Once you get the stuff entered on your load, Shooter is nice and fast.
A nice feature of Shooter is that it will let you put a correction factor in for your scope. If, for example, your scope's adjustments are not 1/4 MOA, but actually only 98% of a 1/4 MOA, that makes a difference.
In my limited experience, it is common to have a ballistic program calculate drop and find it to be consistently off what you experience in the field. If this occurs, you have to fudge velocity or some other variable until things match. The best thing to do is figure out in terms of % what the error is and correct it. Shooter lets you do this.
Similarly, there can be very slight errors in rangefinders and chronographs, but probably not as commonly as in scope internals. Each of these things will cause disparity with ballistic programs.
Folks with better gear, or who are just better shooters/loaders, may not experience this. Of course, if your scope is not consistent in the error, this is meaningless.
Really though, all the advice in the world will only get you started, or get you better faster. One simply has to put a lot of rounds down range and experience how successful their gear is.
