Thank you Rex for the great information on God, Guns, and Guitars! Quick question... I found myself calculating a firing solution the other day in which I had overhead cover to deal with/avoid. A bit of an odd shot. Think of power lines. :) After a lot of searching, I could not find a calculator that produces this number. It looks as if many old school hunters used to look at mid range height, but this seems to be a rough number only viable at shorter ranges. Others state that you look at drop at 2/3 of the range. The only resource I found that definitively listed maximum ordinate for some specific loads is: www.hpbt.org/articles/308.doc I don't see anything in JBM. I don't remember you going through this in Sniper 101. Am I missing something? Thanks.
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racesmith
Mar 17, 2017
Maximum Ordinate
Maximum Ordinate
5 comments
Racesmith,
I too have been searching for info on figuring max ordinate, so maybe Kacie will put a bug in Rex's ear for us! I'm fairly sure Rex briefly mentions it a couple of times in the series, but I can't recall where. Possibly in Advanced External Ballistics and/or the tutorial on spotting.
If I recall correctly, he said something like max ordinate would be about 60% of the distance to the target. Being able to know what that height above the ground is would be nice, especially since the 500 meter range where I shoot has been closed for nearly a year; stemming from allegations of bullets going over the back stop and hitting a barn a mile away!
I am a bit disappointed to not have received an answer in response, but I did figure out the solution. I feel a bit stupid for not figuring it out sooner. In your ballistics calculator, simply set the zero range at the target range. Look for the largest drop and that is the maximum ordinate at that range.
Racesmith,
Excellent solution! Just went to JBM's website and checked the results with the info from your earlier post. Didn't adjust all of the environmentals, but the answer was still darned close! Right around 60% of target range.
This may (or may not) help in getting our 500m range reopened.
Thanks for your post!
There is not much info out there on this topic. It would be nice to have a simple field solution to have without needing a ballistics calculator.
#Geoff Glover - At a local range I use they have an overhead backstop about 1/2 way down the range to the 200 yard line to catch those shots that are way too high. Something your range might want to consider.
Bill,
Perhaps that's in the works. Most of our board of directors got the boot in the last election, but that's a "whole 'nother kettle of fish"!