Ballistic questions: calculating my zero based on POI

CarlTuesday

Lil-Rokslider
Joined
Jul 19, 2016
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Cubicle in Alaska
I've got a new Winchester xpr in 300wsm that is shooting nice groups for the price at 100yd. Shooting Norma 155 Kalahari and 165 oryx.

Kalahari was grouping best at 2.25" high at 100yd. Took it out to 225yd and I'm an inch+ higher than at 100yd...

Is there a way to back calculate what my zero must be given this info? Clearly my round is still rising pretty good at 100 on the arc.

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Do you know your actual muzzle velocity (the velocity on the box is a rough estimate)? Without that, you're just guessing...
 
All the programs want me to enter my zero (far as I can tell)... I guess I can trial and error it, but thought there was a faster way

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Why don't you just zero your rifle at either 100 or 200yds? After that you can confirm your trajectory at other distances.
 
Well...good news is you've got some good speed on that round, if it's still 1" high at 200. You can probably do a bit of figuring to guesstimate your muzzle velocity from that, but as mentioned above, the only way to know is either shoot it over a chronograph or actually run it out further and get proper dope.
 
Probably a 300 yard zero. Why not just shoot it at 300 and see what happens. Also any ballistic program could help figure it. Just plug in the velocity and other info then keep adjusting your zero range til your 100 and 225 yard measurements match the zero input.
 
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