zeroing a scope?

Discussion in 'Optics & Mounts' started by cottontop, Jan 30, 2012.

  1. cottontop

    cottontop Guest

    I heard a guy talking the other day about zeroing a scope. What exactly did he mean and how and why is it done?
    cottontop
     
  2. Belltactical

    Belltactical New Member

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    I'm sure this will open a can of worms and I'm sure everyone will have their own opinions but....

    Zeroing a scope simply means adjusting the scope so that the crosshairs are where the bullets will hit at a specific distance. In my case, my longest range is 152 yds (thank you Nikon for a nice accurate range finder).

    Since I do this over and over and over again on a daily basis, here's the short version i use. After mounting, leveling, lapping the rings and double checking we use a laser boresighter to get close/on the paper. Then fire strings of 3 rounds (remembering of course to remove the boresighter - yes, I did have an idiot working for me who left it in the barrel and no I don't want to talk about it) at 100yds and adjust for windage and elevation until the groups line up with the crosshairs. If its a calibrated mil dot reticle scope you can dial up any range you want from that point (assuming a decent reticle calibrated for the caliber you shoot). Just did one an hour ago. Only took 2 strings of fire to get it dialed in.

    Hope that helps.
     
    Last edited: Jan 30, 2012

  3. cottontop

    cottontop Guest

    Yeah, I understand that. I looked on the internet and found basically your same information. Thanks for responding.
    Anyway, what the guy I was talking about said, was to turn each reticle in one direction until it stops and count the number of turns you made. Then, turn it in the opposite direction until it stops again. Then, turn it the opposite way again half the number of turns you made the first time. Has anyone ever heard of this? It sounds a little suspicious to me.
    cottontop
     
  4. Belltactical

    Belltactical New Member

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    Well, I suppose you could do it that way. Don't think you'll hit anything but you'll likely loosen up some of the grease in the adjustment mechanics so that's a good thing I guess but it won't to anything to align the scope with the bore but hey, have fun screwing your scope dials.
     
    Last edited: Jan 30, 2012
  5. hiwall

    hiwall Well-Known Member

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    The person might have meant centering the reticle and then adjusting point of impact with an adjustable base. Supposed to be some advantage that evades me at this time.
     
  6. Durangokid

    Durangokid New Member

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    Old scopes did not have self centering reticules. The only way to Zero those scopes was with an adjustable base. You only need to follow the detailed post just given by Belltac.:)
     
  7. Muliemaster

    Muliemaster New Member

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    It sets the wind an elevation moa at its center most point of the scope, then u would set the bore zero
     
  8. Belltactical

    Belltactical New Member

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    Sure, but what's the benefit? I don't care where the dials are set when I zero the thing. I only care about where they end up when the bullet goes where the crosshairs are.
     
  9. alsaqr

    alsaqr Well-Known Member Supporter

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    Yes, i have heard of it: It's called "centering the scope reticle". i always center the reticle before the scope is installed on the gun.
     
    Last edited: Jan 31, 2012
  10. Belltactical

    Belltactical New Member

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    Still don't get it. If the scope will run out of room to adjust it to point of impact, then how does centering the reticle in the scope change anything. There a finite amount of adjustment up/down - left/right. No matter where you start from, it's a finite fixed cant be changed adjustment range. You can turn all the dials to the stops and the bring them back to POI but how does centering the reticle change the laws of physics and the total adjustment range of the scope? It's a finite fixed range of adjustment you're dealing with. Centering it won't change anything when you dial it up when firing to zero POI.
     
    Last edited: Jan 31, 2012
  11. Tackleberry1

    Tackleberry1 New Member

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    This would be a good idea especially when moving a scope
    From 1 rifle to another. Setting the adjustment dials to their mid point, then mounting/boresighting would ensure full range of adjustment.

    I encountered this with a scope I inherited. I did not realize that the elevation was 4 clicks shy of being maxed out when I installed the scope. It zeroed fine but had very little left for longer range fine tuning. I had to pull and shim the scope so I could re center the horizontal and use the scopes full range of elevation.

    Tack
     
  12. Belltactical

    Belltactical New Member

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    But if the place you need to be is past the physical limit or adjustment range of the scope, centering the reticle won't change a thing. You'll just dial it more until you hit the stops and it still won't be on target. The only way to fix that is to either get a better scope or use an adjustable base which you should never need with a modern scope that's correctly mounted in line with the bore. You can see it for yourself with a $20 dollar wally a .22 scope made of chinese crap when you mount it on a centerfire and try to zero at 100. You turn it till it won't o anymore and you're stuck.

    I only sell Leuopol's, typically the 3-9's. They happen to have an above-average range of adjustment but he principal is the same. They're nice scopes and have nice large marked 1/4 click moa finger adjustment knobs. When you take them out of the box, the numbers on the dials are all over the place. When you mount it and shoot strings to zero you end up with whatever numbers you end up with. If I hit he stop before its on the X, there's something wrong with either the scope or the mounting (or the weapon I guess). In any case, if I hit the stop before I'm on target I have nowhere to go. Centering the reticle in the scope won't change that. The maximum deflection through the use of the dials is the limiting factor.

    Ya just can't make it move over any more - don't mater where you started from.
     
    Last edited: Jan 31, 2012
  13. Snakedriver

    Snakedriver New Member

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    Belltactical, you are correct. Unless you are going to shim the scope or the base to have more verticle adjustment, I'm not sure you gain anything by centering the reticle prior to installing it. In the end you still have to make any adjustments necessary to move the reticle so that it agrees with the point of impact. Starting in the center may or may not be an advantage.
     
  14. Txhillbilly

    Txhillbilly Active Member

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    The reason that the adjustable base was made years ago was that the scopes available back then were nowhere near what todays optics are in adjustment range.
    Scopes back then had 7/8" main tubes,and the really good/expensive ones had 1",and to have a scope with very many MOA of adjustment wasn't easy.
    Today,scopes can be had with 1",30mm,and even 34mm main tubes,and can have over 100moa of adjustment,so you would have a hard time running out of adjustment.

    When factory actions are heat treated,they sometimes twist a little which causes the scope base mounting holes to become out of alignment with the barrel.Enough that when a scope was mounted,you would run out of adjustment trying to sight in the scope.
    With an adjustable scope base,you could then move the scope so that it was put back in alignment with the bore,and then be sighted in.That's why some people still center the reticle on the scope before mounting them.
    How it's done-
    You center the reticle by counting the clicks and then turn the turrets back half way-Windage and Vertical.Then mount the scope in the rings,mount the boresight tool into the bore,and try to get the scope to line up with the center of the boresighter.Once it is as close as you can get it-without moving the turrets-you set the adjustment screws on the base,and then adjust the turrets to the boresighter.The adjustable base is just for the windage adjustment,not vertical.If your running out of vertical adjustment,you'll need to get a +moa base or Burris Signature Zee rings will do both forms of adjustment if your action is twisted a little.

    With most scopes made today you don't need to do this,but some still do it this way.
     
    Last edited: Jan 31, 2012
  15. theropinfool

    theropinfool New Member

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    I bought a Ruger M77 .243 a few years ago. I wanted to mount a 30 mm scope I had off a rifle I'd sold, and the only rings I could find were the Millet ones that have the screws on both sides. I mounted the scope but nearly ran out of adjustment on my windage while sighting it in. I got home, took it all apart, zeroed the scope, then put it back together, bore sighted it again, and hardly had to adjust the windage when I sighted it in. So yes, you only have so much you can adjust on a dial, but with a zeroed scope, mounting and bore sighting become a lot easier.
     
  16. JonM

    JonM Moderator

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    If you do a lot of zeroing for the less than capable folks like i sometimes do they often have the scope so far out of adjustment that they are no whereremotley near paper.

    Mechanically zeroing the scope back to factory center lets you start from scratch when not being able to look down the bore is possible or laser bore sighting isnt available or practical.

    One way to do it sans bore sighting. Mechanical zero then set a 15 yard target. Take a shot. Aim the rifle at the intended poa from a rest then twist the dials bringing the xhairs to the poi. Back up to 25 yards repeat. Back to 50 repeat. Then 100 and you should be on paper and can adjust from there.

    To verify if your scope is level to the bore be sure your zeroed at 100 yards. Adjust your scope elevation up 15" Aim at the bottom center of a 20" target. If your scope is level your shot group should should be 15" directly above poa. If it is left or right your scope is canted. Loosen the rings and twist the scope only a fraction of a hair towards the direction its off. Repeat.

    Scopes are often canted by "proffessionals" who use bore sighters instead of leveling the action and scope with actual levels.

    Nothing more frustrating than a professional gunsmith mounting a canted scope to a new shooter. Thats how scopes get so far out of alignment they need to be mechanically zero most frequently
     
  17. Belltactical

    Belltactical New Member

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  18. Belltactical

    Belltactical New Member

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    Everyone - I've been doing it wrong for all these years. Obviously I'm an idiot. Sorry. I'll go home now. Bye.
     
  19. JonM

    JonM Moderator

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    Unlikely. I just listed one method. Ther are quite a few valid ways to zero a scope and different types of zeros...