Thanks for the input. I’m trying to figure out if it’s worth it. I usually have my chart on my phone but thought it might come in handy when I’m in the field.I've honestly never used it as I have one of the new Sig BDX setups but I did download it and it seems legit. Easy to use at least...can't speak to the accuracy but I can't imagine it's different than most calculators out there. It has all the inputs that any other calculator I've played with has so I'm sure it uses the same calculations.