GTA
Support Equipment For PCP/HPA/CO2 and springers ,rams => Optics, Range estimation & related subjects => Topic started by: Bimota on January 09, 2022, 03:45:19 PM
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Before I mount a scope I center it. I use a mirror
in a well lit bathroom. Put the scope up against the mirror.
If you see a cross hair and a ghost cross hair turn the
clickers until you only see one cross hair.
Now you can mount your scope.
https://www.youtube.com/watch?v=FOGVJGGQ7tM (https://www.youtube.com/watch?v=FOGVJGGQ7tM)
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When I put the scope directly on the mirror, everything goes dark!
So what I do is get a small hand held mirror and some pennies. I use the pennies to "lift" the scope off the mirror and allow light to shine. ;D ;D
-Y
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The bulbs in my bathroom are crazy bright. I had to unscrew
half of them or it was like being in a tanning booth.
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So define centering your scope. At this stage I think your video and thoughts are....well...bs.
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There are a couple of ways to optically center a scope as well as mechanically centering one. I think they are mostly overkill. I'll mechanically center my scope but I end up sighting in the gun. When you begin sighting the gun your centering goes out the window..
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moved
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So define centering your scope. At this stage I think your video and thoughts are....well...bs.
No, it's not BS, this is just to mechanically center the scopes reticle. You still have to sight in your scope as you mount it. This where PB's have an advantage with the use of laser guides, you can shim rings or swap them (I lap my PB rings) to get the scope centered on AG's.
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This only works if the objective bell is exactly at 90 degrees to the tube.... If there is an angle, either intended (some scopes have an angle on the front to work like a sunshade), or unintended (poor machining), then adjusting a scope using the "mirror method" will not center it....
The idea of using a bathroom mirror, which is vertical with lights above it, however, is a good idea, as the thickness of the mirror allows some light into the scope sideways through the glass.... because mirrors are silvered on the backside....
In order to allow the scope to remain centered (or nearly so), you need to use scope rings that are adjustable in both planes, and ideally shimmed up or adjusted to tilt the scope body downwards to intersect the pellet path at your required zero range....
Bob
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Bob is right about centering the scope. I still use the mirror method and it seems to work well with the scopes I use. I use Sportsmatch rings because they mount the scope on the center of the dovetail and have very little difference between rings.
Where I differ with Bob is that after centering the scope and mounting it I'll bend the barrel to the center of the scope. It's simpler than adjustable rings and doesn't risk damaging the scope with shims.
I adjust the barrel for elevation and windage and check it different ranges on a calm day. Typically I want to be within a turn from elevation center and quarter turn of the windage center. This isn't possible with all gun so adjustable rings may be necessary for guns that are out of whack.
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I just crank it all the way till it stops. Crank it the other way counting half turns till it stops. Then do half that many half turns back. That's always been close enough.
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^x2 .... I also use this method to insure I'm roughly centered.... Then I zero using the turrets as I have not noticed a problem doing that....
There are 2 critical things on mounting a scope however.... Make sure that the vertical crosshair intersects the center of the barrel or you will end up with a cant error.... If you are shooting a mostly long range, use a mount or ring shims (such as the Hawke) to add about 25 MOA of elevation to put you closer to optical zero at 100 yards....
Bending the barrel is a good option for springers, not so useful on many PCPs....
Bob
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^x2 .... I also use this method to insure I'm roughly centered.... Then I zero using the turrets as I have not noticed a problem doing that....
There are 2 critical things on mounting a scope however.... Make sure that the vertical crosshair intersects the center of the barrel or you will end up with a cant error.... If you are shooting a mostly long range, use a mount or ring shims (such as the Hawke) to add about 25 MOA of elevation to put you closer to optical zero at 100 yards....
Bending the barrel is a good option for springers, not so useful on many PCPs....
Bob
What's the easy way to ensure the barrel and vertical crosshair lines are in the same plane?
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Look through the scope and view your reflection in a mirror. Twist the scope in the rings until the reticle simultaneously bisects the muzzle and the objective bell.
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Standard gunsmithing uses the receiver as a zero, the receiver is set in a padded vice and leveled. The barrel will zero on a a vertical plane if it is indeed inline with the receiver. The scope rings then should be zeroed on the same vertical plane using the offset of the barrel center to the scope center.
The scope is then leveled with the same offset and then shimmed or adjusted to your desired poa/poi.
If done correctly, the reticle will align with the barrel, bisecting it.
Ask a licensed gunsmith, they will verify this.
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One method:
https://youtu.be/A-lpJgLtxyg?t=11
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If the receiver is levelled, and the scope also, but the rings are not centered on the receiver, the vertical crosshair will not bisect the bore.... That is the critical thing, or your shots will fall one side at close range and the other side at long range.... Here are all the possiblities....
(https://hosting.photobucket.com/albums/oo221/rsterne/Important/.highres/ScopeCantChart_zps994cd58d.jpg?width=1920&height=1080&fit=bounds) (https://app.photobucket.com/u/rsterne/a/a8f72a68-64d3-494b-98b3-85ba6a7a34e2/p/d55b9d63-466e-44d4-a4f0-9859ffb5747e)
If the scope is not centered on the receiver (as in "A" below), you can get it to shoot properly as follows....
(https://hosting.photobucket.com/albums/oo221/rsterne/Important/.highres/Scope Cant Fix_zpsjtlvn6gb.jpg?width=1920&height=1080&fit=bounds) (https://app.photobucket.com/u/rsterne/a/a8f72a68-64d3-494b-98b3-85ba6a7a34e2/p/c1c4eb32-7617-4d4d-8d50-acf3073ae4fe)
Mount as in "B" and hold gun as in "C".... Not pretty, but it works perfectly....
Bob
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Just for a little monkey wrench. WWII Garand sniper rifle! Yes, the scope is offset. Many WWII sniper rifles of different armies were offset to accommodate loading.
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Just for a little monkey wrench. WWII Garand sniper rifle! Yes, the scope is offset. Many WWII sniper rifles of different armies were offset to accommodate loading.
This would probably work fine as long you adjusted the scope to have the POI to have the same offset from the vertical post as the scope is from the barrel. If the scope is offset say 1" to the left and you adjust the scope so the POI is always 1" to the right of the vertical post.. One inch would be a negligible margin of error in most applications. It's only when you have the bullet cross the vertical Axis that there's a problem with offset sights.
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I don't believe that to be the case.... See example "F" in the first diagram above.... More than likely the rifle was sighted for the most common target range, eg. 600 yards.... That would cause only an additional 1" to the left at 1200 yards.... Airguns are particularly picky with the vertical crosshair does not line up with the bore, because we tend to sight them in at such close ranges....
Bob
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I don't believe that to be the case.... See example "F" in the first diagram above.... More than likely the rifle was sighted for the most common target range, eg. 600 yards.... That would cause only an additional 1" to the left at 1200 yards.... Airguns are particularly picky with the vertical crosshair does not line up with the bore, because we tend to sight them in at such close ranges....
Bob
Bob I think you are a genius. But I'm staying with my statement. You may be right and they might not have sighted it the way I'm suggesting. I'm saying what I said would work.
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To find mechanical center count the clicks from full left to full right then from one end go half the clicks. Do the same thing for up and down. To align the cross hairs hang a plum bob, the farther away the better, I use 100 yds, then align the horizontal cross hair with it. To check this go to the distance you shoot the farthetest and draw a straight perfectly vertical line. Zero the gun at the bottem tip of that line. Click your scope up 5 to 8 minutes, the more the better. Shoot at the bottem tip of the line. You will hit higher up the line but you should hit the line. Now when you have the scope vertical crosshair aligned cover your plum line with it and install a scope level with the bubble centered. Always shoot your rifle with the bubble in the middle. Everything will be square.
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To find mechanical center count the clicks from full left to full right then from one end go half the clicks. Do the same thing for up and down. To align the cross hairs hang a plum bob, the farther away the better, I use 100 yds, then align the horizontal cross hair with it. To check this go to the distance you shoot the farthetest and draw a straight perfectly vertical line. Zero the gun at the bottem tip of that line. Click your scope up 5 to 8 minutes, the more the better. Shoot at the bottem tip of the line. You will hit higher up the line but you should hit the line. Now when you have the scope vertical crosshair aligned cover your plum line with it and install a scope level with the bubble centered. Always shoot your rifle with the bubble in the middle. Everything will be square.
The only problem with mechanically centering a scope by counting clicks or turns is that many scopes the stop at the ends of the adjustments are mushy and vague. Often there's no clear crisp stop. Particularly to far left and bottom ranges. It almost feels as if your damaging the erector tube or the return spring. I prefer the mirror method for this reason. It's not the best way either. The vee block method is better than the other two. The mirror method has been working well enough for me and is the simplest.
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To find mechanical center count the clicks from full left to full right then from one end go half the clicks. Do the same thing for up and down. To align the cross hairs hang a plum bob, the farther away the better, I use 100 yds, then align the horizontal cross hair with it. To check this go to the distance you shoot the farthetest and draw a straight perfectly vertical line. Zero the gun at the bottem tip of that line. Click your scope up 5 to 8 minutes, the more the better. Shoot at the bottem tip of the line. You will hit higher up the line but you should hit the line. Now when you have the scope vertical crosshair aligned cover your plum line with it and install a scope level with the bubble centered. Always shoot your rifle with the bubble in the middle. Everything will be square.
The only problem with mechanically centering a scope by counting clicks or turns is that many scopes the stop at the ends of the adjustments are mushy and vague. Often there's no clear crisp stop. Particularly to far left and bottom ranges. It almost feels as if your damaging the erector tube or the return spring. I prefer the mirror method for this reason. It's not the best way either. The vee block method is better than the other two. The mirror method has been working well enough for me and is the simplest.
Close enough to get zeroed. Like the plum bob down range. I'm gonna' try that.
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I had a long conversation with Hawke about scopes not holding zero and received the link below. Long story short, I have learned about what I call as a rule of thumb for the "comfort zone" (+- 1 turn from the 'center'). Also, that Hawke adopts the V-block for centering. So, I consider the V-block as the 'real' center.
Nevertheless, I'm not comfortable doing the V-block. So, for some scopes I had at hand, I did comparisons = V-block x mirror x counting clicks. From one scope to another, the 'centers' varied, and I had .. coincidences, small and big differences.
I prefer the mirror method as a routine. So, If I want to do it 'wright' for a certain scope, I think that is necessary to center at the V-block, look at the mirror and take notes about the eventual differences . Then, after centering at the mirror and start zeroing, I will be actually considering the V-block center to stablish the "comfort zone".
https://life.hawkeoptics.com/riflescope-alignment/
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I had a long conversation with Hawke about scopes not holding zero and received the link below. Long story short, I have learned about what I call as a rule of thumb for the "comfort zone" (+- 1 turn from the 'center'). Also, that Hawke adopts the V-block for centering. So, I consider the V-block as the 'real' center.
This was going to be my Post.
We must have spoke to the same Tech at Hawke. ;)
A set of "V-blocks on the tube (front and rear) slowly rotate the scope and the crosshairs with "orbit" in a circle, adjust the turrets until it stays centered.
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Btw..
Yes, the right way to wright right is right :-[ ;D
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One time i centered a scope by clicking all the way left then right. It went "Ting" when I got all
the way left and broke. I'm not dumb enough to try that again.
Another time a friend asked me to mount a scope for him. I put the rings on and did not check
them. I mounted the scope. Everything looked fine. The gun was shooting around 6-7 minutes
left. I was wondering if I messed something up. Then my friend tells me the last time he used
that scope it was really windy. Well that explained the "shooting left problem".
I would rather center my scope on a mirror than deal with stupid problems.
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I have done the V block method. Then I found out about the mirror method.
For me the mirror is quicker and easier.
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Thanks for the input of info
I've got a "V-Block". It works pretty good.
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Hmmmm.... Guess I'm all wrong.
I mount the scope on the gun and fiddle with the rotation until the vertical is aligned with center of the bore.
Then I sight in to get on paper at 20yds. Then sight in some more until I hit the POA. Then I move the target out to 35yds. (my average intended range) and fine tune the turrets.
By the time I'm done the break in process is pretty much done and I head on over to Pyramyd Air to order more pellets.... :o
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I have a scope coming tomorrow and I think I will try both the mirror and V block methods to see how they work. Thanks for the posting and all the comments and suggestions.
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I have a scope coming tomorrow and I think I will try both the mirror and V block methods to see how they work. Thanks for the posting and all the comments and suggestions.
Well if you do it right the first time. The second method should be spot on...
-Y