Centering, Setting up and Zeroing your scope-Good info
- Thread starter blackdiesel
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The centering video helped me the most. I checked all my scopes and discovered 3 were off center.
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Thanks for sharing, but pls educate the ignorant. What is the point of centering the scope if the next step after that is going to be to 'off center' it again by zeroing?
Is this to detect scope canting or need for 'no limits' rings?
Is this to detect scope canting or need for 'no limits' rings?
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The main thing is it reduce the chance for parallax errors, give more room for adjustments, and cuts down the amount of adjustment you need to get on zero.
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A good example to use. If you look through a tube, something like a paper towel holder and look at an item in the center of the tube. If you turn the tube slightly you can still see the item clearly. However, the center of the tube is not on the item any longer. So if the pellet were to go to the center of the tube it will not hit the item now.
A real world experience: When I first started I had a cheap scope with parallax errors and it almost cause me to quit. I began shooting from a rest on a table. When I shot from it I had perfect sight alignment so I was able to consistently hit targets with no problem. When I started using a bi pod, my alignment changed so my pellets were hitting a different POI. The groups were still small so I knew the gun was shooting straight but the groups moved to a different location. I would spend time chasing the zero and get back on target shooting off a bi-pod. When I shot off the table again, you guessed it, the POI was different. Once I figured out the problem (by asking other forum members) and learned how to check for and correct parallax errors it was no longer an issue.
A real world experience: When I first started I had a cheap scope with parallax errors and it almost cause me to quit. I began shooting from a rest on a table. When I shot from it I had perfect sight alignment so I was able to consistently hit targets with no problem. When I started using a bi pod, my alignment changed so my pellets were hitting a different POI. The groups were still small so I knew the gun was shooting straight but the groups moved to a different location. I would spend time chasing the zero and get back on target shooting off a bi-pod. When I shot off the table again, you guessed it, the POI was different. Once I figured out the problem (by asking other forum members) and learned how to check for and correct parallax errors it was no longer an issue.
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“ What is the point of centering the scope if the next step after that is going to be to ‘off center’ it again by zeroing?”
Greg is right – As an airgunner who wants the ability to shoot at say 50 yards or more and use the turrets to make adjustments to elevation, I think what you really want is a scope that is centered and zeroed at around 25 yards. That way the scope’s reticle will be back to center when shooting at the further distance of 50 yard. The projectile will be going thru the scopes line of sight at 2 distances – 25 and 50 yard – (your mileage will very). The scopes reticle is more accurate when it is in the center of adjustment and so you will have less error and smaller POI issues at 50 yards. This is the way most FT shooter set up there scopes.
To achieve this you need the scope centered and then mount the scope so it is zeroed at say 25 yards by shimming or adjusting your rings until the rifle is shooting with POI within about ¼ inch without turning the turrets. After achieving this, you can make the final adjustments using the turrets to get the POI where you want it. I have found that on most air rifles you will need to shim the rear scope ring. So here is where adjustable scope rings are worth the extra money.
If you are not going to use the adjustable rings you will need to be a little careful when shimming. You will want to spread out the area of the shim material so as not have a concentrated point of pressure on the scope tube. You can use aluminum soda can – I think they are around .010 thick or anything that is uncompressible and if you need to put multiple layers down then cut the pieces to different lengths and go easy on the torque with the screws so as not to crush the scope tube. Most of the time the torque requirements on the scope rings are less that you would expect. If memory serves me I think it is around 10 inch pounds or less.
If the windage is way off you may need to shim between the rings dove tail and the rail. Your local hobby shop will have some brass strips in different thicknesses that should get you there. Again once you are with about a ¼ inch of your intended POI you can adjust the rest of the way with the turrets. Don’t kid yourself, this is a lot of work. You will have your scope on and off a lot until you find the right shims. You can make small adjustments to windage by rotating the elevation shims in the rear ring toward the opposite side of the intended POI shift direction. Or add a shim to that side of the ring. I hope I was able to properly explain it.
Greg is right – As an airgunner who wants the ability to shoot at say 50 yards or more and use the turrets to make adjustments to elevation, I think what you really want is a scope that is centered and zeroed at around 25 yards. That way the scope’s reticle will be back to center when shooting at the further distance of 50 yard. The projectile will be going thru the scopes line of sight at 2 distances – 25 and 50 yard – (your mileage will very). The scopes reticle is more accurate when it is in the center of adjustment and so you will have less error and smaller POI issues at 50 yards. This is the way most FT shooter set up there scopes.
To achieve this you need the scope centered and then mount the scope so it is zeroed at say 25 yards by shimming or adjusting your rings until the rifle is shooting with POI within about ¼ inch without turning the turrets. After achieving this, you can make the final adjustments using the turrets to get the POI where you want it. I have found that on most air rifles you will need to shim the rear scope ring. So here is where adjustable scope rings are worth the extra money.
If you are not going to use the adjustable rings you will need to be a little careful when shimming. You will want to spread out the area of the shim material so as not have a concentrated point of pressure on the scope tube. You can use aluminum soda can – I think they are around .010 thick or anything that is uncompressible and if you need to put multiple layers down then cut the pieces to different lengths and go easy on the torque with the screws so as not to crush the scope tube. Most of the time the torque requirements on the scope rings are less that you would expect. If memory serves me I think it is around 10 inch pounds or less.
If the windage is way off you may need to shim between the rings dove tail and the rail. Your local hobby shop will have some brass strips in different thicknesses that should get you there. Again once you are with about a ¼ inch of your intended POI you can adjust the rest of the way with the turrets. Don’t kid yourself, this is a lot of work. You will have your scope on and off a lot until you find the right shims. You can make small adjustments to windage by rotating the elevation shims in the rear ring toward the opposite side of the intended POI shift direction. Or add a shim to that side of the ring. I hope I was able to properly explain it.
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I just use the mil dots and a range card instead of using the torrets. I know by having my second zero point at 55 yards the POI will be very close between 55-75 yards (no more than 1/2 mil). Even at 100 yards I only have about 1 1/2 -2 mil holdover. For closer shots, the range card will show exactly how much hold under I need. So it's so much easier for me to just adjust my POI this way. However, I don't shoot FT or benchrest so I don't need the degree of accuracy they strive for.
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Thanks, Killzone! It makes perfect sense now. I think they missed that important piece of information, without which the point of centering seemed unclear.
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