Either do it by shooting at that new altitude (1000' to 3000' is not enough to matter unless your shooting extremely long distance...as in probably a mile or more) or use a program like Exbal that will do this for you. The barometric pressure at your site in location and hunting location have much more to do with how that bullet will fly than altitude, but inputting the altitude can have a small difference if shooting long range with a significant altitude change. Short answer: get Exbal! Have fun!
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