Adjusting reticle vs. Adjusting mounting - Burris Zee rings

[Scot E]

Thanks for all your feedback so far, guys.

The scope has a total of 35 MOA adjustment. The Burris ring set has the offset shims.

However I still don't have a full understanding of how a 20 MOA base or shims affect the impact point / reticle adjustment from 100 to 1000 yards. Furthermore there is the issue of adjusting a scope to its limits and the resulting effect on image quality.

So, let me understand. If I had a 20 MOA base OR installed 20 MOA ring shims on a set of high rings, and say the bullet drop at 100 yards is 2" @ 100, 8" @ 200 yards (similar to many calibers), wouldn't the impact point be too high even at the lowest reticle setting at 100? How many MOA from the bore line vs. sight line does that 2" or 8" bullet drop represent? (I supposed this is affected by the ring height - low med or high.) I bought a 0 MOA base (picatinny rail) because I was concerned I wouldn't be able to adjust down enough to zero at 100 or 200 if I used a 20 MOA base.

Next comes the issue of image quality when adjusting the reticle to extremes. If I do use a 20 MOA base or 20 MOA of ring offset shims, and then need to adjust the reticle down to 3 - 5 MOA from the scope's lowest setting for a 100 or 200 zero, how much image degradation will I incur? Much of my shooting is between 200 - 500 yards. Do I have to give up image quality for the ability to reach out to 1000 yards?

Up til now I have mostly used holdover to adjust for drop. The duplex post, or Nikon BDC. The Nikon BDC system has worked great for my most common conditions, but won't cut it for shooting over 700 yards. I've had a lot of fun chrono-ing my loads and programming them into the software, then seeing how that matches up to the physical reality of holdovers and impact points. Now I want to get into adjusting the reticle for distances.

IMO you really don't have the luxury of worrying about optical degradation. 35 MOA of total scope adjustment is really low for a LR scope and you are going to have to forget about some perks of having your scope perfectly setup and just worry about getting your scope to work within your range. BTW, what scope do you have?

This is personally what I would do for your setup. First I would put your gun/scope in a rigid vice and determine how high and how low you can run your turrets before you start to see the click adjustments start to vary or stop completely. You can do this with a collimator if you have one or you can print out measurements and place the paper at a distance where you can easily get good clarity/focus of your scope but also be able to read the measurements. (You can also verify your scope clicks are adjusting as specified by the manufacturer which will be a huge help in the long run as you begin to shoot longer distances.) This will tell you how much usable MOA you really have and also will tell you how low you can dial to determine your zero point without having turret issues. I would then start at the low point right above where your turrets started having issues and then use the signature rings to get you zeroed at your specified zero range. (I would at least zero at 200 yards) This will give you the most amount of usable turret adjustment. It should also put your scope at it best at the longer distances which is where you really need turret repeatability and optical clarity, etc.

If you want to get enjoy all the benefits of the signature rings or a scope that is perfectly setup for the LR game then you are likely going to have to buy a new LR scope.

Hope This Helps,

Scot E.

 

[bruce_ventura]

Scott's suggestion is spot on. The image blur due to aberrations at the top of your elevation adjustment (1,000 yd range) will not be noticeable. At that distance turbulence will probably cause far more blur than your scope.

As you increase range beyond 500 yds you will find other deficiencies of your Nikon scope. First, lack of turret knobs will make elevation adjustments awkward. Second, lack of windage reticle marks will make holding for wind inaccurate. If you stick with it, before long you will be yearning for a different scope with the proper turret and reticle features for long range shooting

 

[green 788]

Wow...

Lots to "clarify" here.

The erector has it OWN lenses... and they take in light from the objective lens, and transmit it to the occular lens. The position of the erector has absolutely nothing to do with optical clarity.

And it's a good thing for us long range shooters that it doesn't... because we typically run the optic at a 100 yard zero, and dial up from there. We'll dial from bottom to top... but again, as the erector moves, it's only moving a few thousandths of an inch in each direction, and it's never going to be pointed toward the edge of the objective lens--and its transmission of the exit pupil (beam of light) to the occular lens will generally be centered--never toward the edge of that lens either.

The Burris Signature rings are good for getting some additional elevation to enable a rifle's shots to be dialed to longer ranges. I was working with one of our school's test rifles today, and found that it's going to need a boost on the rear of the scope in order to reach 1040 yards... I'll do it with Burris Signatures with the offset inserts. (ordered them about an hour ago from Midway)...

But the notion that moving the erector away from its centered position is going to harm clarity of the scope is simply not true... because the erector's lenses move with it, and the only lenses that don't move with the erector are large enough that the miniscule movement of the erector isn't going to point anywhere close to the lens edges--even if you dial it all the way to any extreme.

Here is a good link to view scope internals... http://www.shootingvoodoo.com/index.php/articles/anatomy_of_a_tactical_bolt_action_rifle__the_rif/

Dan

 

[Dr. Vette]

Dan,

Ever tried it yourself? Ever done exactly as I described above, rotated the scope around and watched the distortion? Distortion is a more accurate word than optical degradation or optical quality and it's probably the word I should have used.

Look at your own link -

do you really think that what is shown below won't cause any problems with what you see and that the image arrives at your eye appearing absolutely perfect?

I'm not saying that there is a lot of distortion but it's definitely there. I never noticed it until I happened to rotate my riflescope one day when checking for optical center, and noticing it convinced me to try and keep my scopes as close to center as I could when using them. I've not tried it on a Zeiss or Swaro or other higher end optic but on a Leupold or Nikon or Burris you will see it.

Test it some day when you're bored.

 

[Scot E]

Wow...

Lots to "clarify" here.

The erector has it OWN lenses... and they take in light from the objective lens, and transmit it to the occular lens. The position of the erector has absolutely nothing to do with optical clarity.

And it's a good thing for us long range shooters that it doesn't... because we typically run the optic at a 100 yard zero, and dial up from there. We'll dial from bottom to top... but again, as the erector moves, it's only moving a few thousandths of an inch in each direction, and it's never going to be pointed toward the edge of the objective lens--and its transmission of the exit pupil (beam of light) to the occular lens will generally be centered--never toward the edge of that lens either.

The Burris Signature rings are good for getting some additional elevation to enable a rifle's shots to be dialed to longer ranges. I was working with one of our school's test rifles today, and found that it's going to need a boost on the rear of the scope in order to reach 1040 yards... I'll do it with Burris Signatures with the offset inserts. (ordered them about an hour ago from Midway)...

But the notion that moving the erector away from its centered position is going to harm clarity of the scope is simply not true... because the erector's lenses move with it, and the only lenses that don't move with the erector are large enough that the miniscule movement of the erector isn't going to point anywhere close to the lens edges--even if you dial it all the way to any extreme.

Here is a good link to view scope internals... Shooting Voodoo :: Anatomy Of A Tactical Bolt Action Rifle: The Riflescope

Dan

Dan,

Coming from a photography background I would argue that your statement is fundamentally impossible. If the erector lenses transmit light, and therefore the sight picture, then by definition they must have an affect on picture quality in some manner. Light transmission by nature is changed every time it goes from one lens to another and even when the light travels through the air in between the lenses it is bent slightly differently each time.

The link you gave actually shows a good example of this. As the erector is moved by the turret the angle in which the light and sight picture passes through the erector lens(es) is altered. This alone can and will cause changes to the sight picture in some manner. Like I mentioned much of this can be accounted for in the scope and lens design but it is there and in mid level or lower scopes especially it is noticeable. And the Nikon the OP has would be in that category IMO.

At the end of the day it isn't the biggest factor that one needs to be worrying about and I think this was appropriately addressed in subsequent posts. Worrying about turret adjustment consistancy and the other issues mentioned are more important, at least for me.

Scot E.

 

[green 788]

If you're wanting to split frog hairs... you could probably in a laboratory find some loss of clarity as you move toward the limits of erector travel...

However, for all practical purposes, you won't see it. Not unless you have a really cheap scope. (and maybe not even then)...

This is a long range oriented forum. Folks here are not going to seriously use Burris eccentrics to center a scope in the rings--there would simply be no reason to do that. Most of us use the entire range of elevation in a scope... we set our 100 yard zeros as close to the bottom of erector travel as we can, this to get as much elevation adjustment as possible, for long range shots...

I put a 40 MOA base on my .338 Lapua Mag... the Leupold Mk4 scope has to be dialed all the way down in order to get to my 100 yard zero (I think I've got about a dozen clicks (3 MOA) left of down-travel when I get to my 100 yard zero.

And I have honestly never noticed any compromise in optical quality at 100 yards, or at 1000 yards... or even with the turret topped out for 1 mile zero... the scope looks the same to me.

Burris offsets are great for jacking up the back of a scope to get it to dial farther... but it's just not reasonable to use them to center a scope for a 100 yard zero--at least not for long range shooters who dial their shots.

One last thing... the depiction of the bottomed out erector shown above it certainly exaggerated for effect... it doesn't move that far, with that much of a slant... it actually only moves around 40 thousandths of an inch in any direction from center, depending on the scope.

Dan

 

[Scot E]

Dan,

With all due respect, I think you need to go back and reread the thread. I get this is a LR forum but the OP is trying to go LR with a scope that isn't perfectly suited for it and he is getting good advice on how to try and make what he has work. The OP has limited travel in his scope and is going to have a hard time getting out to the distance he wants to shoot so the suggestions he has received from multiple guys in this thread is to do just what you state, to use the rings to add 20 MOA of additional adjustment, yes I realize using a 20 MOA base or offset ring inserts doesn't give you a full 20 MOA of additional adjustment, which obviously means he is going to be using most all of his adjustment to have a zero and get to the distance he wants to shoot. To my knowledge nobody was telling him to center his scope with the rings, at least that wasn't my intent. The concept though is to try and get it as centered as possible while still being able to accomplish your goals.

The concept I was trying to explain about scope clarity, picture degradation or distortion is simply this. There will be some change for the worse when you reach or get near to the end of your turret travel (we are going to have to agree to disagree here because I have seen it in scores of scopes) and it is worse with mid level scopes than the scopes you are likely used to dealing with. But the scope he has is a mid level scope so it applies to his issue. So it seems beneficial and prudent to try to minimize it as much as possible even if it is minor. This is a game of detail and minimizing as much error as possible as you obviously know with your background.

Here is a good example. I may be able to get to a mile, lets say this is as far as I will ever shoot, by using all of my turret adjustment on a straight base and rings but to me it makes sense that the farther I shoot the more important it is for me to have the least amount of distortion and the most consistent turret clicks possible. This is simply because the target is smaller, mirage is worse, air quality becomes an issue as far as viewing small details, rangefinder error is greater, etc. So why not use the signature rings, or a canted base, to try to ensure that the distortion that may be found at the turret extremes are minimized? So for me I will always try to setup my scopes so they will be as close to center as possible for the farther distances I shoot. This may put my zero close to the bottom but I really don't care about that because clarity and even slight turret issues at 100 or 200 yards means nothing as far as a kill shot is concerned. But they will affect things more dramatically farther out. Most LR shooters I know never even check change in turret click adjustment all the way through so this whole concept is new to them, hence the reason I brought it up.

I will add 2 things that may put some perspective to this topic. I typically shoot big game to 1/2 mile or a bit over and seldom shoot past 1000-1200 yards for practice. This allows me to setup my scopes differently than guys like you that are at or over a mile which in my mind is more ELR than LR.

Much of my initial optics experience came back in the days when I was really into shooting LR with .22 rimfire and precision airguns. You think this game is detailed, the FT and LR airgun game is even worse! My point is simply that we were aiming at extremely small targets while using the entire turret adjustment just to get out to 150+ yards so we likely became more annal about distortion and other scope issues than even many of the LR guys here would. This experience transferred over to my LR big game hunting and may be unfamiliar or considered overkill by some but in this guys experience it is real and I try to account for it. YMMV

Scot E.

 

[bruce_ventura]

[/quote]

Lots to "clarify" here.

The erector has it OWN lenses... and they take in light from the objective lens, and transmit it to the occular lens. The position of the erector has absolutely nothing to do with optical clarity.

And it's a good thing for us long range shooters that it doesn't... because we typically run the optic at a 100 yard zero, and dial up from there. We'll dial from bottom to top... but again, as the erector moves, it's only moving a few thousandths of an inch in each direction, and it's never going to be pointed toward the edge of the objective lens--and its transmission of the exit pupil (beam of light) to the occular lens will generally be centered--never toward the edge of that lens either…

…But the notion that moving the erector away from its centered position is going to harm clarity of the scope is simply not true... because the erector's lenses move with it, and the only lenses that don't move with the erector are large enough that the miniscule movement of the erector isn't going to point anywhere close to the lens edges--even if you dial it all the way to any extreme…


If you're wanting to split frog hairs... you could probably in a laboratory find some loss of clarity as you move toward the limits of erector travel...

However, for all practical purposes, you won't see it. Not unless you have a really cheap scope. (and maybe not even then)...

…I put a 40 MOA base on my .338 Lapua Mag... the Leupold Mk4 scope has to be dialed all the way down in order to get to my 100 yard zero (I think I've got about a dozen clicks (3 MOA) left of down-travel when I get to my 100 yard zero.

And I have honestly never noticed any compromise in optical quality at 100 yards, or at 1000 yards... or even with the turret topped out for 1 mile zero... the scope looks the same to me…

…One last thing... the depiction of the bottomed out erector shown above it certainly exaggerated for effect... it doesn't move that far, with that much of a slant... it actually only moves around 40 thousandths of an inch in any direction from center, depending on the scope.

Increasing the elevation does not change the location of the light rays on the objective lens. It changes the incidence angle of the light rays on the objective lens. In either case, the light rays always fall uniformly over the entire objective lens.

The erector lens movement is much larger than you indicate. The focal length of the objective lens for a typical long range rifle scope is 6-9". For an average 7.5" focal length objective, 30 MOA of elevation change corresponds to 0.15" of turret travel, not "40 thousandths of an inch". Some scopes have over +/-50 MOA of travel, which corresponds to about +/-.25".

Burris Signature Rings can provide up to about 17 MOA (30 mm) or 25 MOA (1") of correction. That is usually enough elevation bias for most shooters to get out to 1,000 yds.

In your case of the .338 Lapua, a mile shot requires about 60-75 MOA of elevation from a 100 yd zero, depending on the specific altitude, inclination, BC, MV, etc. By using a 40 MOA base, you are reducing that elevation requirement to 20-35 MOA from the optical center of the scope. As other posts have stated, this is a good approach for multiple reasons.

At an incidence angle of about 30 MOA, you would need a trained eye to notice the image blur due to off-axis aberrations in the objective lens. It does not, however, require an optical laboratory to observe this level of image blur. One way to observe this effect is to set up two identical scopes, one with an optically centered reticle, and the other with the reticle shifted 30 MOA. Then look through them at a target about 50-100 yds away. The target should be high up off the ground to minimize turbulence-induced image blur. Any person with good visual acuity would notice the difference in resolution and contrast in one scope vs the other instantly. It's not "splitting frog hairs". It's an obvious effect if you do the side-by-side comparison. It will be observed with just about any scope at a price point below $1,500 due to the wide use of simple achromatic doublet objective lenses.

Under many shooting conditions, however, shooters may not notice the image degradation, even though it's there. Trying to assess optical performance at a shooting range, for example, can be very misleading because the image resolution and contrast are usually limited by turbulence in the air, not by the optical performance of the scope.

 

[Shootin4fun]

Thanks for all the input/feedback, guys. I've learned a lot from your answers and the general "debate". Many good points about starting with biased mounting and changing image quality due to reticle adjustments. The latter is something I hadn't thought about until recently, despite my lifelong involvement in photography, cinematography, and optics. I'm about to build it all up tonight and shoot this weekend.

I should note that the 1" Burris Sig Zee rings did NOT come with the elevation inserts as the phone consultant at Big C told me they would. (You were right, Bruce.) Looks like I'm going to have to order them from elsewhere because they're not even listed in their online catalogue. We'll see today if they compensate me somehow for false information. If not, I will yelp them a negative.

I needed to build this rig on a pretty tight budget, so $500 was the limit for the scope..."mid-low end" as described by some here. Only 35 MOA of adjustement is part of why I started this thread. Nevertheless it should serve me well for the time being. I was also concerned that a full 20 MOA rail would put me so high at 200 that even at the bottom of the scope adjustment range I might be above my prefered zero. So with the Burris sigs I have some intermediate choices.

Thanks again for all the helpful info!

 

[Scot E]

Not sure if you can fit it in the budget but Burris makes an insert kit that gives you many options to choose from, I think .005, .010. 020 for the 1 inch set. If you think you may end up with other signature rings down the road you can use them in those as well.

Good Luck!

Scot E.

 

[Shootin4fun]

Not sure if you can fit it in the budget but Burris makes an insert kit that gives you many options to choose from, I think .005, .010. 020 for the 1 inch set. If you think you may end up with other signature rings down the road you can use them in those as well.

Good Luck!

Scot E.

Yes, I am ordering them. I figured the same about using them in the future on other rifles I hope to get. But due to near term limited shooting opportunities and me chomping at the bit to break this thing in, I'm just going to mount with the 0 MOAs tonight.