Zero a rifle for 100 with only a 30 yard range?

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bigfug

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I dont think I am gonna have time to find or go to a range thats got enough distance for me to zero my .243 in at 100-150 yards like I would like, so prob gonna have to use H&H, and this is a new rifle/scope. How high should I be on paper at 30 to be zeroed in?
 

doctorjj

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Depending on the height of your scope, you'll probably actually want to be a touch low at 30. I could use Bulletflight on my iPhone to get you really close if you can post or PM me the details about the bullet and load you are using as well as the scope height.
 

HiredHand

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Tulsa Firearms has a computerized ballistics program. You input the height of your scope ab ove the bore axis, type of ammunition, and a few other details. The program can then tell you where your bullet will strike at various distances based on the zero you choose. So, my point is these programs do a pretty decent job of getting you where you need to be.
 

Ksmirk

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Do a search for JBM Ballistics Calculator, you plug in the variables and it spits out ballistics! just a sidenote they are not 100% correct but will get you in the ballpark. I use it to get me on target then fine tune from there so far it's been dang close. One thing if it ask you for say height over bore don't guess but measure! don't know that it would be that far off @ 100 yards but a 1/4" does tend to grow when you stretch out the yards. Later,

Kirk
 

tran

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Depending on the height of your scope, you'll probably actually want to be a touch low at 30. I could use Bulletflight on my iPhone to get you really close if you can post or PM me the details about the bullet and load you are using as well as the scope height.

You are correct...
 

ez bake

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Ballistics programs can be quite a bit off depending on elevation, air pressure, and temp. Keep that in mind if you're zeroing in a temp-controlled indoor building.

Scope height isn't a super-critical precision measurement - change it 1/4" and see what the ballistic programs say - not much difference (maybe 1/10th of a mill way down range).

I don't know that I'd have the confidence to take a shot at a deer if I hadn't at least shot the rifle in real-world conditions at the range I was expecting to see one (even if in warmer temps and different air pressure).
 

doctorjj

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I just ran Bulletflight and to zero at 100 with a 1.5" sight height, you'd need to be 0.7 inches low at 30 yards. A better zero might be 200 and for that you'd need to be 0.5 inches low at 30 yards. That's with an 80 gr bullet.

For a 100 gr Core-Lokt, you'd need to be 0.6 low for 100 yard zero and 0.1 inch low for a 20 yard zero.

I also ran various temperatures, pressures and humidities and non of that changed anything at 30 yards. Obviously as you get further out it will affect it but for your zeroing purposes it does not. Even at 200 yards though, the effect on the bullet going from -20 up to 80 degrees F was only .3 inches. Also at such close ranges, a change in the sight height only affected the relative impact by as much as the sight height was changed.
 

bigfug

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supposed to be in the low 70's on Saturday, so temp shouldnt be too off for opening weekend. I really dont think if I get a shot it will be 100yards, probably less knowing OK terrain. I am going to try and check it at 100 before I leave if I can. If not when I leave the lease on Saturday, I'll pace off 100 check my zero again, not worried about spooking the deer should be over it by the next weekend.

ETA, it will be a 100gr core-lokt, 22 in barrel, not sure on bore over axis, but you guys definitely got me on the right track. All my other rifles were hand me downs, roughly sited in, and most definetly on paper, I just had to adjust slightly, and I did have the room to stretch their legs a little bit.
 

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