Then, if at 18.9 inches of mercury I readjust for the original 250yd zero, what will my new drop at 550yds be, given that the 250yd zero with 26.8 inches of mercury gave me a 47" drop?
Load is 7mm Hunting VLD at 2,780fps.
Thank you for your help.
Alvaro
If you're contemplating a 500 yard shot, you really need to develop the capability to figure this out for yourself.
Or to put it another way, you shouldn't rely on someone else to figure it out for you. Especially on the internet.
Go to this link (Berger ballistics calculator) and input your numbers. You don't need barometric pressure, just altitude. Then check to see if this model holds true for your locale:
http://www.bergerbullets.com/ballistics/
