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Why don't scopes & rings come with witness marks???

Discussion in 'Rifle Country' started by AKElroy, Sep 1, 2009.

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  1. AKElroy

    AKElroy Member

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    I have mounted a number of scopes over the years, and it is always frustrating to true the plane of the reticle to the bore centerline. Why don't rings & scopes come with witness marks to make it easier to mount keeping the reticle level??
     
  2. ants

    ants Member

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    Probably because mounting holes, mounts and rails aren't cut true, either.

    And the real proof is in the shooting.
     
  3. AKElroy

    AKElroy Member

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    Agreed, but having a single line running the length of the scope on the same plane as the verticle crosshair would definately help to get it close. I mounted a scope last night, eye-balled as best I could.

    I tested it today on a level purch, pointing at a known level referrence, and found it way off. Frustrating. I would have done this last night, but my horizontal referrence was in the dark.
     
  4. highorder

    highorder Member

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    Some, perhaps many people cant the rifle slightly when they actually shoot.

    The crosshairs should be level when the rifle is held in the shooting position, as opposed to actually being true to the rifle.

    imo, I think the scope should be mounted true, and the rifle held level, but thats not always the case.
     
    Last edited: Sep 1, 2009
  5. usmc1371

    usmc1371 Member

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    I have to agree with you it would make it alot easier to get it close, better than the eye ball method.
     
  6. 627PCFan

    627PCFan Member

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    +1 for highorder. Im right and cant to the right naturally with my Tikka which is how I have it set. If you bench the gun the top of the reticle is slightly to the left-
     
  7. Temp430

    Temp430 Member

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    Scope Cant Error

    I glanced over a the following short article on scope cant error:

    http://www.microlevel.biz/cant_errors.html

    What I took away from it is that a 5 degree cant in a scope's cross hair amounts to a 3.75 inch error at 500 yards.

    Most people can easily eyeball a scope's vertical cross hair to be within less than 5 degrees of true vertical. So unless you shoot at ranges > 500 yards, don't worry about it.
     
  8. SeekHer

    SeekHer Member

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    Don't line up to the horizontal but the vertical, much easier to do...the corner of any building works fine...
     
  9. rcmodel

    rcmodel Member in memoriam

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    A pair of $1.99 bubble line-levels from the hardware store work in the basement.

    Put one on the rifle receiver or magazine bottom and level it.
    Then put the other one on the top of the scope turret or cap and level it.
    Tighten the screws.

    Voilà!
    The scope and rifle are on the level!

    rc
     
  10. AKElroy

    AKElroy Member

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    The scope I mounted yesterday is an old K-4; the turret is domed as is the adjustment knob. To make it worse, the rifle is a 94 AE; with the reciever, well, angled. I was able to purch the rifle on a half wall & get it lined up with the window blinds. Close enough for a .30-30---
     
  11. matrem

    matrem Member

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    Not ideal,but unless you change the turrets & as long as you hold the same cant, it means nothing at any distance.
     
  12. Ratshooter

    Ratshooter Member

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    Mount your rifle in a gun vise and use a square to sure the screws in the buttplate are vertical. Make sure whatever your gun vise is sitting on is level. Hopefully you have your rifle pointed at the corner of a neighbors house or some other vertical object.

    If nothing else tack a small peice of rope on the wall with a weight on it. Line the vertical crosshair up with that. You don't have to use a gun vise either. I you my front rest and sand bags on the kitchen counter top.

    Also getting your scope square with your rifle will help correct the canting you are doing with your rifle.
     
  13. jim in Anchorage

    jim in Anchorage Member

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    OK, I may be thinking wrong here, but if you are holding at the intersection of the cross hairs[like a dot, really] what does it matter what the horizontal/vertical lines are doing?
     
  14. matrem

    matrem Member

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    I will retract part of my post # 11. Gravity does pull straight down.
    Needed to edit for those who "holdover".
     
    Last edited: Sep 1, 2009
  15. Uncle Mike

    Uncle Mike Member

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    It doesn't...UNLESS you adjust your crosshairs. Then as you raise the intersection of the crosshairs, the POI will also walk off left or right in addition to raising.

    If you get some machinist parallels and put them inside the receiver on your bolt rails(bolt action rifle), you then build them up till the flat bottom of the scope is setting on them.

    Most scopes have a flat, and square to the reticle, bottom on them at the turret.

    Most firearms have a flat, and square to the bore place machined somewhere on or in the receiver you can access.
     
  16. Runningman

    Runningman Member

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    Because reticles can be canted within the scope tube.

    Bought a Reticle Leveler more than 15 years ago. I see they are discontinued now but this will give you an idea how they work. http://www.midwayusa.com/viewProduct/?productNumber=360476

    But what if you shoot off a benchrest at 100, 200, 300, and 600 yards. Typically you are going to be moving turrets and it is frustrating enough sometimes dealing with wind conditions without adding in another factor.
     
  17. Runningman

    Runningman Member

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  18. Maverick223

    Maverick223 Member

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    From my experience the most accurate way to plumb a scope is to use a good carpenters level across the action and then use a plumb-bob at distance to get everything true. An alternative method is to use a bubble level attached to the action and the aforementioned plumb-bob. The level will also aid in shooting at distance. :)
     
  19. usmc1371

    usmc1371 Member

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    "What I took away from it is that a 5 degree cant in a scope's cross hair amounts to a 3.75 inch error at 500 yards."

    Show me a HUNTER with a HUNING Rifle who can hold 3.75" at 500yds under HUNTING conditions and I will be really impressed. I don't think I have to worry about that with my ruger all weather 300wm and factory loads. Maybe off a good bench, under ideal conditions, I could tell my sub 1/2 moa accurate Les Baer .204 was off 3.75" at 500 yds but i doubt it.
     
  20. Pulsar

    Pulsar Member

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    If Im hunting and I see a deer at 500yds and Im taking the shot. I will have more that enough time to set up for a rock solid shot.
     
  21. highorder

    highorder Member

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    Wow, I'll pass on that shot.

    I'm either less confident, or more honest.
     
  22. Dr. Tad Hussein Winslow

    Dr. Tad Hussein Winslow member

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    A. It's an excellent question and should be done. It's a lot easier/cheaper/faster/more convenient than a separate bubble or other leveler with or without plumb bob, or eyeballing it.

    B. Yes, it can and does matter what the hairs are doing, even if the center is always on the target, if your hold is at all different each time. The bullet goes up and then back down - not left and right. Think of this way. If you turn the gun 90 degrees to the left and shoot and have the center of the crosshairs on the target, do you think it will hit the bullseye? No, it won't - not even close - because now the bullet is going LEFT (the "old up") instead of up, and just keeps going further and further left as there's no counteracting force against it as gravity would be against an up vector. If you're canted left 5 degrees, smaller error (5/90ths of the full 90 degree error), but still an error.

    C. No it doesn't matter for most any hunting scenario to be off by up to 10% or so toward 90 degrees, but it can't HELP either, and some of us are OCD about our guns. And it DOES matter for long range practical/target shooting.

    You're probably more honest, and/or have less 'false and imprudent confidence'.
     
  23. Clark

    Clark Member

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  24. Pulsar

    Pulsar Member

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    this is a hijack
    but i wrote that about someone hunting and not have a good shot to have the 3 inch make a difference
     
  25. rockstar.esq

    rockstar.esq Member

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    I think it's a good idea, even if the "Huntin-accuracy" folks dismiss it there's the simplicity of being able to dismount and re-mount your optics with some repeatability due to the witness marks. Personally I'm still somewhat annoyed that it's standard practice for every maker to do their own thing. Ambiguous names like "high, medium, and low" don't tell you squat about how close the objective will be to the barrel. It's almost funny that there are literally thousands of different cartridges and they each have a distinctive name, yet every scope ring maker seems to believe their version of "low" is the right one. For the record I think the idea should be expanded to have witness marks and tension indicators on all scope hardware. All rings should be named by their actual measurements. All scopes should be labeled with their minimum scope ring & mount height.

    Probably the most pitiful part of all of this is that scopes were created to help the shooter get all the accuracy they can out of the rifle yet the mounting hardware is hopelessly disorganized and totally lacking in meaningful datum points.
     
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