scope levels

S

Shadow9mm

New member
I understand the basic premise behind them. I also know I probably don't need one but I kinda want one. My questions are these how easy are these.

How much of a a difference would one actually make in group size?

Is it more of a target thing, or useful for hunting as well?

how easy it it to use, I would assume you have to come off the gun and re-check your level between each shot.

For those of you that have one or have used one

are there any particular ones you would recommend or that I should stay way from?

do you actually use it when you are shooting?

is it worth the $
 
I find the anti-cant devices/levels annoying. I spent more time making sure the anti-cant level was level than shooting. I just plum/level the cross hairs when mounting the scope and then don't worry about it anymore.
 
Canting causes a small horizontal shift in bullet impact. Formula to calculate how much is bullet drop at target range times the sine of the cant angle. If the bullet drops 360 inches at 1000 yards, a 1 degree cant moves the point of impact 6.3 inches (0.63 MOA) in the cant direction

It's easy to have repeatable cant angles shooting at stationary targets. Pick a reference at the field of view side or bottom edge with the reticle on target then align the reticle end to it. Doesn't matter if the scope is canted a tiny bit because it'll be repeatable across all shots.

All of which is why I never used a level unless I used aperture sights on bullseye targets. Front sight had a bubble level. I put a mark on the bubble that gave a 1 MOA horizontal POI change to use in team matches. When the coach gave me a small sight correction, I canted the rifle to make the adjustment without going out if position to twist the rear sight windage knob.

Here's a scope with an internal level.....

http://www.opticstalk.com/us-optics-internal-anticant-bubble-level_topic25393.html
 
Last edited:
I recently tried one after sixty years of shooting precision rifle. They’re of little value in my opinion. You have to come off gun to look at them for one thing, and group size did not improve. They sound better in theory than they deliver in actuality.
 
I use levels on all my rifles now--mostly because I'm not very good at having exactly the same hold/pressure points shot to shot. A slight change in position in my case can make a huge difference in what I see as "level"--it's amazing sometimes how "crooked" the reticle looks when the level says correct for cant. This also happens with my digital ATN scope which has "on-board" software for cant correction. If I put the scope level on the scope tube out around the front ring and sight/shoot with both eyes open--I can often "superimpose" an image of the level while maintaining sighting through the ocular and not have to come off the sight picture to check.
 
Having a scope level let’s you eliminate another variable, cant. That error looks like the letter ”C” depending on the angle of cant.
If you go from 0 cant to 90 degrees of cant, you increase the error, magnitude depends on the range of the target. (And yes you increase the vertical error more holding the gun up side down).
Simple example: Assume your barrel and scope are fixed and boresighted with a 1” height difference. As you tilt the gun clockwise the POI starts moving left and up with more rotation. At 100 yards (everything else being the same) the POI moves along a circle to 1” to the left of the Point of Aim (POA), if the gun is rotated 90 degrees.
But at even only a 10 degree cant the POI is about a tenth of an inch from the POA.

Now let’s go out a bit farther and click in 3 MOA elevation..... you just magnified the error. How much is your physics homework for the weekend. :)
 
Last edited:
I've been using the Wheeler swiveling anti cant device for several years now.
Easy to watch when you have both eyes open.
Even my hunting rifles have them.
Stay closed in most circumstances. Opportunity at game at longer distances usually allow time to open up and get set up properly.
 
TXAZ said:
Having a scope level let’s you eliminate another variable, cant. That error looks like the letter ”C” depending on the angle of cant.
If you go from 0 cant to 90 degrees of cant, you increase the error, magnitude depends on the range of the target. (And yes you increase the vertical error more holding the gun up side down).
Simple example: Assume your barrel and scope are fixed and boresighted with a 1” height difference. As you tilt the gun clockwise the POI starts moving left and up with more rotation. At 100 yards (everything else being the same) the POI moves along a circle to 1” to the left of the Point of Aim (POA), if the gun is rotated 90 degrees.
But at even only a 10 degree cant the POI is about a tenth of an inch from the POA.

Now let’s go out a bit farther and click in 3 MOA elevation..... you just magnified the error. How much is your physics homework for the weekend. :)
Click to expand...
Does "boresighted" mean the bore axis and LOS intersect at 100 yards?

How much bullet drop from the bore axis is there?
 
I use one on my 22lr benchrest rifle, like others have said it's hard to hold the gun perfectly for every shot without one. The dot you shoot at is .0050 on a ara target, not having the rifle sit on the bags the same way each shot will ruin your score even at 50yds.

 
Thanks Bart; it also highlighted: "The Long-Shot article makes two other important points. First, cant error increases with distance, and second, cant-induced windage errors are worsened by mounting your scope high above the bore axis." I think that people who don't need cant devices simply are very good at maintaining consistency with their hold at all ranges--meaning if they are inducing a cant--at least they replicate the same degree of "error" in all their shots. That is way beyond my meager skill level.
 
Last edited:
The value of a level also depends on what kind of shooter one might be. I remember a rancher who brought a rifle into a shop I worked in. He wanted a new scope put on his rifle, we levelled the scope square with the rifle. The rancher, upon picking up the rifle, shouldered the thing, and quickly issued forth with much disdain. He swore up and down that his scope was put on crooked. We cradled the rifle, stuck a level on the scope cap and invited him to partake in a moment of peekage. The guy became much nicer and expressed a mild degree of shock and disbelief.

In speaking with the feller, we learned that he was not a bench shooter and cared little for shooting anything that didn't pose a threat to his livestock or that which might find itself served on a plate. He naturally canted the rifle at the shoulder, done it his whole life, and didn't feel the need to correct the situation. Quite respectfully he asked if we could cant his scope for him.

If you're a bench/bipod shooter into the long range sport, have no natural tendency to cant a shouldered rifle when shot from the hind legs, or have a degree of OCD- then a scope level might be for you. I don't believe there is a place for one on a working rifle (as in farm/ranch, HD, or job related). But whether it's one that's built into the ring, one that looks like a stand alone scope ring, or a simple string level laid on a scope cap- they are interesting things to play with. If you're shooting a cradled rifle at a bench, just about anybody can eyeball their rig well enough to square it up to the point that any unperceptable cantage probably won't matter. There are too many videos of folks trying to shoot targets between 1 and 2 miles away that don't seem to use levels.
 
Am trying to square cross hairs when mounting scope. When shooting, am rotating rifle to one side till the cross hairs are obviously off. Then rotate to other side and split the difference. Can be done fairly quickly.
 
stagpanther said:
I was just quoting from the link you posted. If I had to guess--which is all I can do-- the further the distance from the bore the reticle is the more "exaggerated" the cant angle becomes?
Click to expand...

Remember how scopes are adjusted for range zeros. Bullet drop at target range plus scope height above the bore is how much above point of aim on target the bore must point when the bullet leaves.

If the scope is 2 inches above the bore and the bullet drops 198 inches at target range, the bore must point 200 inches above point of aim on target.

How much above point of aim must the barrel point if sight height above the bore is 1.5 inches? 199.5 inches.

If each situation had the rifle canted 90 degrees, one will put bullets half an inch futher right than the other. One dropping 200 inches and the other 199.5
 
Last edited:
All I can think to add is that some people have a better natural ability to feel or see when the rifle is level. I generally am one of these people and dont use a level.

Some people are naturally pretty bad at it, and they may benefit from one. Depending on your natural ability, you may want to consider them.

Also, it depends on what shooting positions and how far you shoot. If only a bench and the window of a hunting blind at 200 yard shots, I would think not necessary regarding of how good you are at naturally leveling your rifle. If you are hunting on the side of a mountain with whatever base you can find to put a backpack on, that might be a really good time to have one. The angle of the mountain may throw your sense of level off.
 
Remember how scopes are adjusted for range zeros. Bullet drop at target range plus scope height above the bore is how much above point of aim on target the bore must point when the bullet leaves.

If the scope is 2 inches above the bore and the bullet drops 198 inches at target range, the bore must point 200 inches above point of aim on target.

How much above point of aim must the barrel point if sight height above the bore is 1.5 inches? 199.5 inches.

If each situation had the rifle canted 90 degrees, one will put bullets half an inch futher right than the other. One dropping 200 inches and the other 199.5
Click to expand...
Thanks for that. I believe what the quote you linked to in the first article was referring to is induced windage error as being exaggerated in a scope mounted high relative to the bore axis assuming they are parallel (as opposed to a scope being mounted lower and closer to the bore axis). If I understand your example above correctly, the 90 cant is actually no cant at all, in other words the bullet's trajectory is perfectly aligned with the line of sight with no windage deviation.

For whatever reason(s) I'm not especially good at maintaining a consistently repeated position of the rifle when shooting off floppy bags or packs. Without a doubt I'm a part of the error equation. That said, when I use a level for cant it's easy to see through the scope even a minor canting of the rifle results in a movement of windage enough to move the POA through the scope off the target altogether pretty easily.

Here's an article that I found which does a good job of explaining things the way I understand them, which includes an explanation of why the degree of windage error as well as elevation error exceeds that of bullet drop as a result of canting the rifle. The article mentions a perceptual cant limitation of about 5 degrees for a shooter--which I take to mean that our visual acuity is limited to about 5 degrees within true vertical. In my case it's probably worse than that--in shooters that find they don't need levels I would assume either their perceptual acuity is better--or they are naturally better at holding the same consistent hold.
 
Figure 3 in that link shows bullet drop from the trajectory maximum ordnate. Drop has to be measured from the line of fire on target where the barrel points.
 
You must log in or register to reply here.
Back
Top