How much eye relief is enough?

Discussion in 'Long Range Scopes and Other Optics' started by bookworm, Jun 29, 2009.

  1. bookworm

    bookworm Well-Known Member

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    What is the smallest eye relief you would be comfortable with on a 300 win mag?
     
  2. LouBoyd

    LouBoyd Well-Known Member

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    There are a lot of variables. The total wight of the rifle. Barrel length. Bullet weight. Stock design. Whether it has a brake, Where you position the scope on the rifle. But the most important thing is how you hold and control the rifle with respect to your body. For me 3 is marginal shooting a WIn 70 sporter (about 10 lb w/scope no brake) offhand wearing safety glasses. 3.5 to 4" is comfortable. I'm 64 and not very strong.

    Assume your 300 Win Mag weighs 10 lbs total with the scope, has a 26" barrel, and you fire a 190 gn bullet at 3000 fps with no brake. 0.0025 seconds after the primer fires the gun >will< be recoiling rearward at about 13 feet per second, If you're shoulder, hands, and arms don't slow it down the scope will hit your eyebrow about .03 seconds later. To stop the rifle your body has to convert most of 25 ft-lbs of kinetic energy into heat in your body. Some will be converted to heat in the recoil pad. Where else can the energy go to stop the rifle? Yes, you can do that and not let the scope hit you, but you can't be careless about it. You have to actively control the rifle and do it without flinching. That takes some practice. Letting your head (with eyebrow) move some along with the rifle and your shoulder increases the distance the rifle can move before the scope could hit you.

    If you're woried, videotape yourself shooting the rifle from the side with the scope mounted well forward on the rifle. Put white marks with tape on the side of your rifle at 1" intervals so you can see just how far the rifle and your head moves in each video frame. If the gap closes to an inch more than than the eye relief of your scope then you should be concerned.
    The remedies are
    1. work on your holding technique.
    2. add a muzzle brake
    3. get a longer eye relief scope.

    NTSC (US standard) videos are .0333 seconds per frame.
     

  3. Coldzero

    Coldzero Active Member

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    Mar 22, 2009
    Sight picture is also something to consider in this. You just want to get to the point where you have no black around the edges of your sight picture. You'll get a perfect circle of picture with no black edges and once you get that...stop.

    Alot of people keep putting their eye closer once they have already gained the sight picture, one of my friends did and he ended up with an "eyebrow". Once you have that sight picture you can measure it. Most scopes generally offer about three inches of eye relief.

    So it can be trial and error on finding scopes that have enough eye relief when you use rifles with more recoil. I have had a mate who bought a rubber eye piece just in case and I had another friend put a muzzle brake on because he didn't want to spend more money on another scope.

    I believe alot of eye relief problems come down to poor sight picture with people creeping on the scope till they are an inch away. It can also be funny shooting positions ie going from benchrest to field positions and eye relief changing with a different stock weld.

    Cheers,

    CZ
     
    Last edited: Jul 10, 2009
  4. sniperboy

    sniperboy Well-Known Member

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    Gday to all

    Coldzero mentioned "You just want to get to the point where you have no black around the edges of your sight picture". I have a few rifles and have scopes ranging from doctor, weaver, kahles, leupold and so on. Out of all of them i have not got a problem with seeing through the tube, up to my shoulder and perfect viewing. But with my nightforce scopes i can never get the black around the edges away. I adjust the eye relief but still cant get rid of it. What maybe the problem?

    sniperboy
     
  5. Coldzero

    Coldzero Active Member

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    The general rule of thumb is the higher the magnification on the scope the less eye relief, but some brands do offer longer eye relief.

    You may have had a perfect fit on your rifles, stock weld wise, so that you had a perfect picture once shouldered. Move your eye back and forth until you get no black around the edge, it may be that is has extra eye relief. If this is the case you may just have to shift your scope so it is spot on (perfect sight picture) when put to your shoulder.

    Just remember if you shoot prone with the nightforce make sure you adjust the sight picture for that type of shooting. Also, some food for thought, you will see no black in your sight picture if the scope is mounted too close.... recipe for disaster (weatherby eyebrows!).

    Nightforce scopes, such as the 5.5 - 22 NXS have a whopping four inches of eye relief!! Their scopes are intended for handling the higher recoiling rifles such as the .50 BMG, not a problem for the lighter stuff though. You just may have to mount it a little further forward.

    Hope this is helpful.

    Cheers,

    CZ
     
    Last edited: Jul 9, 2009
  6. glockman55

    glockman55 Well-Known Member

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    3.7-4.0" Of course it depends on the Rifle.