One word: CANTThe higher the scope off the bore the more effect even one degree of cant has. If you could sight in through the barrel, cant does not matter, in all other conditions it does.Remember, when you are sighted in with an absolute zero cant does not matter(assuming you are consistantly canted). At all other distances you will only be "on target" in one plane.For longer shoots, a bubble level is necessary.-YScott does a great job explaining all this here:https://www.gatewaytoairguns.org/GTA/index.php?topic=72099.0
Whatever works best for you is the right height above bore. For me, I sight all rimfires and airguns in using the Point Blank Range method which means I get the scope as low as possible and practical.
Would the ultimate scope height simply be "as low as possible" or is there actually an advantage to raising it up a bit?Is it possible that a higher mounting is actually sometimes advantageous, for instance when shooting at longer distances?
The optimum height is the height at which it is most comfortable to you. There is a common misconception that a high scope aggravates cant error. It does not. Refer to the link at the end for more detail but suffice it to say if you are using the proper aim point (i.e. a mildot or by dialing the turrets), the scope's height does not influence cant error. What it will do is influence the error arising from a ranging error. That is a different type of error, and one that favors neither a low scope nor a high scope in all cases. It favors a low scope for shots at short distances, and a high scope for shots at long distances. http://www.szottesfold.co.uk/2012/03/high-scope-and-canting-end-of-ancient.html
Oh I know, the simple trigonometry is exactly why I struggled to grasp it for so long. But I could not deny it after trying this: I started by zeroing both scopes at 25 yards. Then I shot groups at 50 yards to find the necessary holdover for each...2 mildots for the low scope and 1 mildot for the high scope. Then I canted the rifle 45° and shot a group through each scope, using the proper mildot for the 50 yard distance. Sure enough, the POI was the same for both. Why is that? Well, when I found the 50yd holdovers, what I did was find a mildot in each scope that superimposes on the same spot at 50 yards. From that point on I can angle the gun any way I want and they always superimpose on each other at 50 yards. So if I'm canting the gun 5 degrees and aim 2 mildots down with the low scope, or 1 mildot down with the high scope, I am aiming at precisely the same spot on the target at 50 yards. Therefore however much I miss my intended point of aim is precisely the same for either scope.
A simple question, though I suspect that the answer might be slightly complicated.Assume you had no conflicting issues with cheek weld position, breech height, magazine height, etc etc etc. Would the ultimate scope height simply be "as low as possible" or is there actually an advantage to raising it up a bit?I ask because I've seen plenty of air rifles with scopes mounted very high, when the mount could easily have been much lower.--------------------Background:I typically do backyard pesting at extremely close range, say 6 to 10 yards, but I also use the same gun for hunting, out to a max of maybe 60 yards. Because of the very close pesting range, a lower scope minimizes how much turret adjustment or holdover I have to do. (I'm trying to NOT add offset iron sights) I recently got an MTC SWAT 10x30 for my Flashpup, and am going through some extreme mods and finageling to get that scope as low as i can, which is VERY difficult with a short eye relief scope on a bullpup design. The MTC's adjustable MOA base makes the situation even worse.I've make good progress so far, but I might be able to go another 1/4" or so lower, with extreme effort. (and damaging the rifle's resell value) I'm wondering if it's worth it, or am I even totally making a mistake?Is it possible that a higher mounting is actually sometimes advantageous, for instance when shooting at longer distances?
In all fairness it's not much of test at those short ranges with a flat shooting gun. There's more accuracy error than cant error at those ranges. You really need to stretch it out to at least a hundred
Now if the scope is set higher above the receiver the "near zero and far zero" happens at longer distances which benefits the longer distances, however it also makes the proper holdover/under more critical for the closer targets since the closer poi is also lower at the closer distance.............
QuoteIn all fairness it's not much of test at those short ranges with a flat shooting gun. There's more accuracy error than cant error at those ranges. You really need to stretch it out to at least a hundredNo, not necessary to demonstrate it. First of all, the extreme cant angle of 45 degrees produces a large error...equivalent to a small cant angle at longer distance. Secondly, I used a “not-flat-shooting” rifle producing only about 750fps and a low-BC pellet to produce a meaningful amount of drop.I know you’re skeptical. So was I.Perhaps you can explain how two identical points of aim can produce different points of impact?
As Scott has lamented at times, it is a myth that refuses to die, and people will continue to cite intuition and poorly crafted math to explain why cant error is worse with a higher scope.Anyway when you figure out how identical points of aim will produce different points of impact, please share your wisdom with us.
Let me say right up front, I am a firm believer in a good cheek weld but,The World Championship Field Target event is coming very soon…in ItalyAt least two of the very best riflemen in the world that will be shooting there, are from Northern California.Neither of these gentlemen allow their cheek to touch the stock.I do.They don’t.They are championship level shooters.I am not.