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Old March 23, 2014, 05:36 PM   #1
Swilly
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Redfield scope won't hold zero

A good friend of mine just picked up a used older Ruger 77 in 270 win at a Cabela's store. It came with a nice set of Leupold mounts and so he bought a Redfield scope. He let them mount it and bore sight it. Now, this afternoon he stopped over to sight it in at my farm and I asked who mounted the scope because it was clocked 90 degrees off. He said he was wondering why it took them so long to bore sight it, lol! But the real problem is that after we corrected it, it won't hold zero. Is it possible to over travel with the wind age and elevation adjustment knobs? I geuss I don't know if there is a stop at maximum travel because I never had to find out. I can just imagine some kid in back at where he bought it cranking on the adjustment because he did t know enough to put the darn thing on right in the first place!
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Old March 23, 2014, 08:47 PM   #2
geetarman
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I am surprised that was not noticed when the rifle got picked up? How could that happen? Is the owner really new at this?

It is possible the scope has been damaged.

Do you hear anything rattling around?
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Old March 23, 2014, 08:59 PM   #3
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Every scope (at least all that I know of) hold zero best when they are as close to the center of the adjustments as they can be.

When your friend's scope was mounted improperly, it got moved "way off center".

So the question is, how to get the adjustments back to center so you can start over.

It is tedious BUT you have to determine the total number of "click" adjustments the scope has. If you are lucky, you can check the scope maker's website or call them and they can tell you that number. If not, you can learn the number for yourself.

Start (talking about windage adjustment) by moving the adjustment all the way to the LEFT. You will feel it stop when you get there. Now comes the tedious part! Very carefully move the adjustment all the way to the right as you count the number of clicks before you reach the stop on the RIGHT.

Take that number and divide it by 2. Now carefully count the number of clicks as you move back toward the LEFT. When you reach the number you determined by the "division problem" you have now reached the center of the adjustments once again.

If it still won't hold zero after all this, send it back to Redfield

Don't ask how I learned how to do this.

Final point: If you ever buy a used scope (I have found some great deals on occasion) I strongly suggest you do this for both windage and elevation adjustments before you try to zero the scope to your rifle.
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Old March 23, 2014, 09:02 PM   #4
Swilly
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It's his first hunting rifle. He has no experience with scopes of any kind. Up until recently, the area we are from was shotgun only for gun deer season. I can see how it would be easy for him to overlook it anyways. No, the scope doesn't rattle or make any noise as if there was anything loose inside. I am just worried for him at what kind of service he'll receive if it was damaged by cabelas staff.
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Old March 23, 2014, 09:04 PM   #5
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I lied, his marlin .22 has a scope. But regardless, he is the kind of guy where the guns stay in the safe unless he intends to use it on game.
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Old March 23, 2014, 09:05 PM   #6
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Counting the total number of clicks would be mind numbing.

It would be FAR easier to make a mark on the adjustment when at the end of travel with either a lacquer stick or felt tip marker and then count the turns to the opposite end of travel. Then divide by two and move in the opposite direction. It won't be as accurate as your method but it will sure be quicker and at 25 yds. it should be easy to boresight on a target or use a laser boresighter and a garage door.
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Old March 23, 2014, 09:10 PM   #7
Swilly
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Thank you

Thanks for the info guys. It's good to know that there is a positive stop in the adjustments. I was somewhat worried that it would be possible to say, turn the knob until it fell apart internally. But then again, I only have a rough idea of what exactly the apparatus that holds the crosshairs is constructed.
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Old March 24, 2014, 08:52 PM   #8
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Quote:
Counting the total number of clicks would be mind numbing.
You could equate "mind numbing" to very tedious BUT that is the only way to get the crosshairs "centered" in the tube.

As I suggested, the easiest method is to call the scope mfg. and find out the number of clicks between the stops.
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Old March 24, 2014, 09:59 PM   #9
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Quote:
You could equate "mind numbing" to very tedious BUT that is the only way to get the crosshairs "centered" in the tube.
Getting the crosshairs exactly centered in the tube really isn't very important. What IS important is getting the mechanical adjustments close enough to boresight and get the first shot on paper. Further adjustments will most likely be needed to get the zero where you want it.

The goal for me is to get the first shot on paper at 25 yards and make gross adjustments to get to my initial zero. Missing the mechanical zero point with a typical scope means I can be off 15 clicks or more and not have a problem.

Too carry it to extreme would be to mount your scope in a vee block and auto reflect an image on a first surface mirror and buck in. Then rotate 180 degrees and take out 1/2 the error with the knob and half by re-bucking in the scope. You do that for both the horizontal and the vertical. Point is: it isn't worth the effort for the small gain in precision.

It would be very important if we were talking about theodolites or transit squares.

It just does not make sense to me to make the job more involved than it needs to be.
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Old March 25, 2014, 05:07 PM   #10
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My method

I count the clicks, limit to limit on windage & elevation & set half way. Next, I get my small vee blocks, put the scope tube (where the rings will be mounted) in them & looking thru the scope I rotate it around and watch the crosshairs. If the count was right the crosshairs will rotate on center. If they don't, adjust them until they are on center. Your scope is now optically centered.
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Old March 25, 2014, 05:21 PM   #11
geetarman
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^^^^^^^^^^^ Exactly right.

I don't normally count the clicks. Just count the whole turns. If stop to stop goes 20 1/2 turns, then I will back off 10 1/4 turns. That is plenty close enough to get on paper.
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Old April 13, 2014, 04:48 PM   #12
Bart B.
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Toolman's V block test is the only good way. Most scopes have more adjustment one way from optical center to the stops, but not the opposite way, which is not necessarily mechanical center of the adjustment hardware.

Once the scope's adjustments are on optical center, it's good to see how far off parallel with the bore axis the scope rings are. Boresight the scope to the barrel then see how much off its optical center the barrel's aligned with it.
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Old April 13, 2014, 07:03 PM   #13
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Mounting a scope at 90 degrees shouldn't hurt anything. In fact I know of a few people who do it on purpose. Especially on rifles used on dangerous game. It leaves more room over the ejection port to load faster and lessens the chances of an ejected case hitting the adjustment knob and falling back in the action jamming things up. It won't work with all reticle types, but with a standard crosshair scope does just fine. Most scopes have plenty of adjustment range and exactly the same windage and elevation adjustment range. The scope doesn't care which way it is mounted.

You just have to remember that the windage adjustment now controls elevation etc.
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Old April 13, 2014, 07:08 PM   #14
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Quote:
Counting the total number of clicks would be mind numbing.
Patience is a virtue, as are diligence and attention to detail.
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Old April 14, 2014, 05:42 AM   #15
Bart B.
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Southpaws often mount scopes 1/4th turn counterclockwise on left-hand bolt actions.

Can someone explain how a non-damaged scope could be less repeatable with an adjustment for elevation or windage off center?
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