Math question on scope adjustment?

[WEATHERBY460]

22-250

I am dead on at 100 yards
My ballistic calculator says at 400yards, come up 4.7 moa or -19.5"

If my scope says 1 click 1/8" how the heck many clicks do I go, and in what direction?

Thanks...i think it is 37.6 clicks in the following the down arrow, but not sure?

Thanks!

 

[NomadPilot]

To be nitpicky, it matters if your clicks are 1/8" or 1/8 MOA. At longer ranges, you'll need more clicks if it's 1/8".

For now we'll assume it's 1/8 MOA for ease of math.

1/8 = 0.125
4.7 MOA / 0.125 MOA per click = 37.6 ~ 38 clicks. So you were right up to this point.

And you want to turn in the UP arrow direction. That will move your POI 4.75" high at 100 yards, and dead on at 400, assuming correct dope.

 

[Buffalobob]

The arrow points UP for moving the bullet strike UP. For simple memory " Go UP tp go UP".

There are eight 1/8 per inch. You want to move up 4.7 IPHY then that is 4X8 = 32 clicks plus 0.7 IPHY = 6 clicks Total is 32+6 =38

If your scope is set up in inches then you need to toogle the units in your ballistic calculator so it gives you IPHY instead of MOA. Life will be simpler and more accurate

 

[britz]

just to add to what BB said... most scopes in the US are IPHY. Nikon, bushnell, Tasco, redfield, burris...

your upperend and European scopes are usually MOA.

 

[4xforfun]

Funny story,

A few years ago I got all anal about the whole inch/moa thing. I was not real sure about my Leupold scope.....did it move in inches or moa. I called Leupold for the answer. I talked to several people up the food chain and they all said the same thing...."MOA and inches mean the same thing". When I asked them if 30 MOA and 30 inches at 1000 yards is EXACTLY the same....they said....."YES.....EXATLY" !!!!!!


Go figure.

To this day I am not sure. How about NF Scopes.

 

[WEATHERBY460]

Can I check this at 100 yards by aiming at the bull, and the bullet should hit 19.5" high?

 

[NomadPilot]

Can I check this at 100 yards by aiming at the bull, and the bullet should hit 19.5" high?

No. It'll be 4.7" high at 100.

 

[WEATHERBY460]

ohhhhhhhhhhhhhhh

its beginning to click now...lol

 

[WEATHERBY460]

I shot, and am about 8" high at 400 yards....so that means I need to move the scope in the "down arrow" direction........am I right?


i am bad a my left/rights/up/downs...lol

 

[jmden]

4.7 MOA at 100yds is approx. 4.7 inches, or to be more exact, multiply 4.7 by 1.0471996 to = 4.92 inches at 100 yards. 4.7 MOA at 400 yds is approx. 19.69 inches.

1 MOA converted to inches at 100yds is 1.0471996 inches, or just 1 inch to make it easy, but 1 MOA at 400yds would be 4 x 1.0471996 inches. That's how I got the ~19.69 inches above.

Take the yardage to target, divide it by 100 and that is what 1 MOA at that yardage will be in inches. That's close enough for estimated MOA typically.

1000yds-1MOA is 10" To be more exact-- multiply 10 by 1.0471996.

600yds-1MOA is 6"

200yds-1MOA is 2"

559 yds-1MOA is 5.59"

...etc.

Sorry if that's not helpful. Jon

 

[jmden]

I shot, and am about 8" high at 400 yards....so that means I need to move the scope in the "down arrow" direction........am I right?


i am bad a my left/rights/up/downs...lol

Yes. 2 MOA down should get you very close if your shooting ability and equipment and ammo are all working very consistently. But again, if you don't know what units your scope is adjusting in, you need to find out and then start using those units in your ballistics program and start thinking in those units, whatever they may be.

 

[WEATHERBY460]

I actually shot a 1" 3 shot group somehow at 400yds....but i have also shot basically a 1 hole 5 shot at 100 group...so the gun and ammo are working.

I was a little off to the right also, but next time I shoot I will use a level to make sure I am holding square.

I want to get the height right, then tweak everything else.

Can it happen that you are dead set even left/right at 100, then the further out, you are off one way or the other...what causes that?

 

[jmden]

"Can it happen that you are dead set even left/right at 100, then the further out, you are off one way or the other...what causes that?"

Wind, spin drift, coriolis potentially. Might want to check out Bryan Litz's new book:

http://www.longrangehunting.com/forums/f19/new-book-applied-ballistics-long-range-shooting-43573/

And perhaps pick up a copy of Carlock's first video:

Long Range Hunting DVD

Some of this will start making alot more sense after going through these resources.

 

[WEATHERBY460]

Im good.....as far as left rights...just need a couple clicks to fix that. i shot pretty good today with the calm wind. actually really good.

I seem to be 31 clicks (1/8 per click) between 0@100 and 0@400 . I chronoed this 50 grain bullet at only 3600fps. Little slow, but it shoots super for me.

I am going to menards to buy some wood to make a better target at 400 yards.

I am surprised at the ballistic charts of how much bullets drop from 400-500 yards.

Thanks for the help!