Should I use density altitude over GPS altitude when inputting into shooter? Density altitude being acquired by pressure reading I.e. A kestrel reading. Where as gps uses triangulated off satellite. Will there be a difference in the solution shooter spits out? Thanks

Can't say I've used shooter in a while but for just about any ballistic calc if you have a kestrel and know the correct station pressure don't fool with altitude anything if you don't have to. Though for your specific question I believe density altitude would be your best bet. Density altitude basically takes current environmental conditions and relates that to a standard altitude where those conditions would be true.

I have used both input modes shooting to 1000 yards and found no difference in results as long as the inputs entered into the fields are accurate. There is a good explanation of this in Bryan Litz's book, Ballistics for Long Range Shooting.

If you have access to pressure use it over altitude. Altitude gives an approximation of pressure. PS Remember to click the "Pressure is absolute" box if you do. This is whay I like about my simple Leica 1600b, quick access to yards, pressure, and angle, though the temp gauge on it is useless if held in my pocket. There is much more to this and if you have the time to learn you should, but since this is the "Starting out" section, I think a simpler answer is better.