Scope height question


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merrill
June 24, 2012, 01:56 AM
I shoot a .270 Winchester. My scope is about 2.5 inches above the bore. The MV is about 3000fps with 130 gr. bullets. To have a 200yd zero, how high should I be at 100yds? The charts I have seen are for scopes mounted 1.5 inches. I would appreciate any info.

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jmr40
June 24, 2012, 08:11 AM
Go to the range and shoot it at 100 yards. That is the only way you are going to know for sure.

meanmrmustard
June 24, 2012, 08:23 AM
Sight the rifle in at gradually increasing ranges, if possible. At 100, sight the rifle in at a distance above the bull that puts the bullets flight path at a 200 yard zero. At 100 yards, with the mv and bullet weight described (not sure of you barrel length though) I'd zero at between 1.25 inches to 1.5 inches above the bull. This will get you in the 10 ring at 200. Good luck.

bhk
June 24, 2012, 09:36 AM
+1

Charts are only approximations. I generally keep moving back until I get my gun sighted in exactly at 200 yards and then check point of impact at 100. THEN RECORD that 100 point of impact with that rifle/ammo/scope height combo for future reference, because it is usually easier to find a 100 yard range to resight the rifle should you disassemble it or change out the scope.

Just curious, why do you have your scope mounted so high? Seems you would lose any possibility of a good cheek weld.

merrill
June 24, 2012, 01:38 PM
You are correct about the cheek weld. It is mounted high because I could not get good eye relief with the mounts and scope I have. I had to mount a picitanny (sp?) rail to move the scope far enough back to get the eye relief I wanted. I have noticed that many scoped AR type rifles have the scope mounted high and that affects the trajectory of the bullet. Most of my deer kills have been at 175+ yds. and the shots were ~3-4 in above point of aim. My normal point of impact at 100 yds. is 1.5 in. above zero. I don't have access to a two hundred yd. range.

rcmodel
June 24, 2012, 01:59 PM
I just ran it through "Remington Shoot" free ballistics software.
http://www.remington.com/pages/news-and-resources/downloads/remington-shoot-software.aspx

With a Rem factory 130 grain SP load:
1.5" scope height.
100 = 1.51" high.
200 = Zero.
300 = 7.05" low.

2.5 scope height:
100 = 1.01".
200 = Zero.
300 = 6.55" low.

I'd change the zero to 1" high at 100 yards for an approximate 200 yard zero and see how it goes.

rc

Flintknapper
June 24, 2012, 03:42 PM
Just ran it through QuickLoad (QuickTarget) and RC's findings match.


It is an approximation, not knowing the BC of the bullet you will be using, but use his figures and you will be very close.

merrill
June 24, 2012, 04:03 PM
Rcmodel and Flintknapper, that is just what I was hunting for. Thanks a bunch.

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