scope placement from bore vs distance


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trigga
August 7, 2012, 03:11 AM
like the title says, how much of a factor does it play when we're talking about distance? I have a savage 17hmr which the scope is placed very low to the bore vs something like a colt sp1 sporter with a scope which is high above the bore, I know they both are accurate guns but how much of a difference will the gap from the colt's scope make compared to the savage as an example at 100 yards, 200 yards, and so on...

i recently bought a cetme for cheap and it came with a mount, only thing about it is the scope will sit fairly high and i'm having second thoughts about it. (whether to invest in something nice or just something that works)

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MtnCreek
August 7, 2012, 09:17 AM
It's going to be a bigger issue with the .17 than it would with a longer range centerfire. From your far zero out, there's no difference, far zero to near zero to muzzle will be more extream with a higher scope. Higher glass can also cause some issues w/ long range shooting; if the rifle is out of plumb, the higher glass effects poi more. Go to handloads.com and play w/ their balistic calc. You can adjust your sight hieght, leaving all other info the same to get a feel for how it effects you.

henschman
August 7, 2012, 03:04 PM
Height over bore definitely makes a difference. By way of illustration, the 5.56 55/62 grain and 7.62x51 147 grain have basically the same trajectory out to 600m. The M-14 has sights low over the bore, and when zeroed at 25m with 147 grain 7.62, it's second zero is at 200m. For the AR-15, with it's sights high over the bore, when zeroed at 25m with 55 or 62 grain 5.56, the second zero is out at 300m.

Don't worry about trying to imitate the height over bore of another rifle, on one with completely different ergonomics. Generally on standard-stocked rifles like your .17, you want to mount the scope as low over the bore as you can, to minimize how much you have to build up the comb in order to get cheek weld. Just mount the optic as low as you can, and dope out the trajectory. It will be different for every rifle, anyway.

basicblur
August 7, 2012, 03:17 PM
You might want to get the free Remington SHOOT software (http://www.remington.com/pages/news-and-resources/downloads/remington-shoot-software.aspx)?
You can plug in the figures for scope height and bring up some eye opening trajectory graphs (a picture is worth a 1,000 words).

trigga
August 7, 2012, 11:11 PM
thanks guys, that chart really helped

stubbicatt
August 9, 2012, 09:47 AM
Also one must consider that the human being will never be able to hold a scope perfectly level without the aid of a bubble or something. If your scope is mounted on the carry handle of an AR 15, waaaay up there in the air, and you cant the rifle 1 degree, the shot dispersion will be significantly greater than the same situation with the scope mounted closer to the bore.

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