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Thread: Scope height

  1. #1
    Regular Poster buck52's Avatar
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    Scope height

    Does anyone have a tip on how to reliably measure the height of the scope cross hair from the centre of the bore please?

  2. #2
    Don't mean to sound sarcastic but have you tried a ruler! You will be within 1/8th of an inch just by offering it up. JC

  3. #3
    Regular Poster buck52's Avatar
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    Thought about that but being a sad bugger I want to be more precise, if I am 1/4" out it will mean a lot at say 300 yds.

  4. #4
    Your ballistic program says it will mean a lot, meanwhile, back in the woods, there are so many other and much larger variables, that come into play when shooting for accuracy out to 300 yrds that it will pale into insignificance. What calibre and bullet weight are you using? JC

  5. #5
    JC275 is right. Putting a bore guide in or even a cleaning rod will give you two things to eyeball. A ruler or a caliper can then be held over the rifle and the measurement will be good enough for country work. Rgds JCS

  6. #6
    Distance from the top of the front objective, straight down to the top of the barrel. Subtract half the diameter of the objective and add half the diameter of the barrel at that point. ~Muir

    PS: I looked at my 7x57 data on my ballistics program and changed the scope height from 1.5 to 1.75 inches to see the difference. At 300 yards the POI went from -4.47" to -4.42". That's less than 1/16 of and inch. What the devil are you hunting??
    Last edited by Muir; 15-06-2010 at 12:31.

  7. #7
    Regular Poster buck52's Avatar
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    Quote Originally Posted by JC275 View Post
    Your ballistic program says it will mean a lot, meanwhile, back in the woods, there are so many other and much larger variables, that come into play when shooting for accuracy out to 300 yrds that it will pale into insignificance. What calibre and bullet weight are you using? JC
    .308, 150 grn Hornady SST @2860fps

  8. #8
    Regular Poster buck52's Avatar
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    Quote Originally Posted by Muir View Post
    Distance from the top of the front objective, straight down to the top of the barrel. Subtract half the diameter of the objective and add half the diameter of the barrel at that point. ~Muir

    PS: I looked at my 7x57 data on my ballistics program and changed the scope height from 1.5 to 1.75 inches to see the difference. At 300 yards the POI went from -4.47" to -4.42". That's less than 1/16 of and inch. What the devil are you hunting??
    Thanks for that Muir, midges mate, thats what I,m killing, I reckon 150 grn .308 ought to do it

  9. #9
    Quote Originally Posted by buck52 View Post
    Does anyone have a tip on how to reliably measure the height of the scope cross hair from the centre of the bore please?
    if you want to be precise,remove the action from the stock,measure with a set of verniers the distance from the top of the scope to the bottom of the action,then measure the dia of the action and take one measurement from the other

  10. #10
    Quote Originally Posted by buck52 View Post
    .308, 150 grn Hornady SST @2860fps
    You could be in luck then. 223435678 is the answer, the snipers telephone number. From a dead on 100m zero these are the adjustments, in MOA, for each 100m increase in range to 1000m. Eg: 100m to 200m add 2MOA, from 200m to 300m add 2MOA, from 300m to 400m add 3MOA or from 100m to 400m add 7MOA. Obviously this is only a guide and you will have to check it out with your particular load and rifle but I bet you will be supprised how close it will be. It also doesn't help that much for the inbetween ranges but its a good place to start.
    JC

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