A level-headed Andy McLachlan lets us into a few of his secrets about how to conquer the dreaded scope cant.
Those of us who have been shooting a long time often take for granted that we are holding our crosshairs nice and level when we take a shot. What I mean by ‘level’ is that our sights are level at ninety degrees to the horizontal plane for the vertical line in our scope image, which should also be at a perfect right angle to our gun’s action.
This is often easier said than done to achieve. I have lost count of the number of shooters whose scopes I have looked through to discover that their crosshairs are far from a perfect ninety degrees, usually with a slight incline to the vertical post of the reticle depending upon whether they are left- or right-handed.
So why is this such an important issue to iron out? Well the problem with scope cant, to give it its proper name, is that if you are holding the gun in a non-level position when you take your shot, the pellet will not be flying its way perfectly down your line of sight.
Instead, it will fly either one side of this or the other, depending on which way the scope has been incorrectly angled when fitted to the gun’s scope rail.
This is particularly frustrating for the beginner, who will not recognise the issue and will spend hours adjusting the windage knob on the scope as they try to dial out the error. They will manage to do so at one particular range, but will discover that all other ranges continue to show the fall of shot not perfectly in line with their crosshairs.
As you can imagine, this never-ending search for a perfect zero will continue unabated until the root cause of the problem is resolved, namely that the scope clamps are loosened and that the scope is brought into proper line with the rifle’s action and barrel.
When we shoulder a scope-mounted gun, we all do our best to get a nice ninety-degree site picture with our vertical crosshair appearing perfectly upright and showing no sign of cant. Most of us are capable of doing so to a reasonable extent.
The only problem is of course that you might have the scope nice and square, but the gun, due to how the scope is mounted to the action, could very well be off square.
Fortunately, this is one of the shooting issues that is most easily resolved. I bet that everybody reading this owns a spirit level of one sort or another. All that needs to happen is for you to track down yours from the depths of your toolbox. While you are at it, see if you can find another, as two will speed up the process and stop any fiddling about.
Once you are suitably armed with preferably a couple of spirit levels (not those massive things used by builders, as they have to fit on the gun’s action and on top of the elevation adjustment turret on the scope), the first part of the exercise is to mount the gun in a suitable stand that secures it in the true vertical position without you having to keep hold of it.
I don’t mean a death-like grip, just so the gun doesn’t want to twist either way without support. Then carefully slacken off the scope clamp mounting bolts with an Allen key just on one side of both front and rear mounts so that you can just rotate the scope itself.
The next step is to place the first spirit level onto a flat location on top of the gun’s action. If the level is suitably small, an ideal location is either at the front or rear of the scope rail. It shouldn’t take much to locate that bubble perfectly into the centre of the level, indicating a nice level action for your rifle.
We now know that the gun is perfectly straight. All we need to do next is to match up the position of the scope to reflect this. Locating your other spirit level, place this on top of the scope’s elevation turret and simply rotate the scope carefully until both air bubbles indicate that all is perfectly square.
Finally, carefully retighten the scope clamp bolts using minimal torque until the scope is securely fixed in position. If you have done this thousands of times as I have, you will know when you have achieved the correct torque/tightness.
If you haven’t, just turn the screws until you can’t rotate the scope any longer and then give them a maximum of an additional quarter of a turn. The correct tool for the job is a mini torque wrench which will allow the user to set the tightness to the manufacturer’s specifications, but most of us, including me, don’t own one so just be careful and don’t overtighten!
You can then be perfectly sure that your scope is perfectly centred and that your pellets will fly straight along their intended path without landing one side or the other of your intended point of impact.
Obviously, as distance increases, the wayward pellet fired from a canted gun will travel further away from the intended POI, often meaning, in the case of outdoor target shooting, that the killzone of a small target might be missed completely.
Our editor Mike Morton wrote an excellent article on how to use this method of proper scope alignment correctly a year or so back. It really is an easy fix for those shooters experiencing shots that fall away from the centreline of the scope and can transform accuracy problems with a quick fix that doesn’t involve cash, stripping guns down or cleaning gun barrels.
Now that we know all is perfectly square with the relationship between the gun and the optic, all that remains is to make sure that the gun is held in a perfectly vertical position when in the shoulder. This is where the fitment of a spirit level to help level the combination assists us even more as we take careful aim.
There are many available options when it comes to scope-mounted spirit levels and I won’t list them here. All you need is something that you can preferably look at when your eye is looking through the scope.
Most of the available options fit the scope body or the mount. Some swing out to allow a clearer view, with some just sitting on top of the mount that can be harder to view on occasion.
If you have properly mounted the scope and ensured it is perfectly level, the use of an additional level will allow you to be one hundred percent confident that you will experience no cant and that your pellet will be winging its way to the target perfectly in line with your crosshairs.
As an example of how cant can and does affect our fall of shot, I was recently using my current favourite gun, my AGT Vulcan 2 at the Leigh 53-yard indoor range from the bench. I had of course used my described method to make sure that all was square and was shooting reasonably good groups at this long range.
However, I noticed that the fall of shot was ever so slightly to the left of centre. On getting back home, I fitted a scope mount level to my combination and wondered if it would improve results.
At my next visit to the club, and carefully squaring up the combination prior to firing, my wayward shots had totally disappeared and were now bang in line. After experimentation, I discovered that I had been holding the gun with a very slight bias away from vertical.
Using the level has helped me to get rid of this handling issue and allowed those fifty-yarders to remain bang on. Such an easy fix, but such seriously good improvements!