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POI Sighting in height at 100 yards

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Outrider View Drop Down
Optics Apprentice
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Outrider Quote  Post ReplyReply Direct Link To This Post Topic: POI Sighting in height at 100 yards
    Posted: February/03/2011 at 22:49
Can anyone suggest a good, practical resource/guide for point of impact settings above xero on 100 yard targets when sighting in rifles in common calibers (.243, .25-06, .270, .280, 7mmRM, .308, .30-06) using traditional factory loads so that 200 yard POIs (theoretically at least) hit dead on xero? For example, I have seen suggestions ranging from 1 inch to 3 inches above zero settings for a .30-06. I will be hunting powerlines from shooting houses with distances ranging out to 400 yards. It is my understanding manufacturer ballistics tables are based on test barrel data which differ from actual stats produced by typical hunting rifles.
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308 Sav View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 308 Sav Quote  Post ReplyReply Direct Link To This Post Posted: February/04/2011 at 04:59
The test data will be higher usually than your real riffle. It will be close to your 200 yds and off at bit at 400 yds. If you are going to shoot an animal at 400 yds shoot your rifle at 400 yds to know what it is not the theoretical drop.

As far as giving you a sight in for those calibers there are too many different bullet weights and loads to give you that answer. 

A good place to start is with something like this.

choose your load 
set the zero at 200
Set target distance at 100
It will give you the theoretical 100 yds site in.

Like I said before this is a good start to go to the range and to test what your loads and rifle actually shoot. I would never shoot an animal ay a distance I had never shot my rifle at and knew its drop.
Gerald Baker
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8shots View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: February/04/2011 at 05:38
+1 what 308 Sav said.
 
JBM Ballistics is also a good place to scratch around.
 


Edited by 8shots - February/04/2011 at 05:40
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jonoMT Quote  Post ReplyReply Direct Link To This Post Posted: February/04/2011 at 10:12
These guys are right. There's too much variation among loads and barrels to use manufacturer's drops (or for that matter, tests done by powder manufacturers or anybody) as more than a rough guide. In my experience, something like a .30-06 or .308 sighted in 3-4 inches high @ 100 yards will typically have a max. point blank range (inside a 8-10" radius) out to 300-350 yards. 400 is stretching it since drops start increasing dramatically past 300.

You can either get the data you need (muzzle velocity, bullet specifics such as BC) to use a ballistics calculator like JBM to get a better profile or go to a range, sight in 4" high @ 100 and then go shoot out to those distances mentioned to see what you get for drops. You'll want to do that anyway.
Reaction time is a factor...
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