How To Optically Centre A Scope

Tony Fouracres talks us through a very important part of the process in setting up your scope, one that is often over-looked by many shooters….  

Being a passionate Field Target shooter, I like to have all my scopes fully optically centred before fitting, so that I am always looking through the very centre and the clearest part of the glass.

This can be achieved by a number of various different methods; some count the total number of clicks on the turrets from one end of travel to the other, and then halving the number. Do beware of using this method though as with some cheaper scopes you may damage the internals when they rub against the inside of tube at full travel. Also, by coming back exactly half the number of clicks on both the elevation and windage turrets may still not give dead centre – you will be close but not exactly there! 

Others use the “mirror method”, by looking at the reflection of the cross hairs in a mirror placed a few millimetres from the end of scope. Speaking personally, I have found this method to be somewhat difficult and could never really seem to get things spot on when doing it this way.

For me, the method that seems to work best is to rotate the scope 360 degrees in a homemade jig that I have come up with, and watching where the cross hairs travel in relation to a known point on a wall or target board located about 10 yards or so away. The “path” travelled by the crosshairs can often be around 4” high by 9” wide (similar to the shape of a rugby ball), as the scope is turned through the full 360 degrees if the scope is not centred. You then simply adjust the elevation and windage turrets a few clicks at a time until when it is totally optically centred the cross hairs will stay on exactly the same point you are focused on.

My own homemade jig is solid, ridged, fully adjustable for length of scope, and has served me well over many years, but I have also known people use a shoebox or similar by cutting an arc for the scope to sit in!

Finally, I’ll make mention of the fact that I always use Sportsmatch ATP66 fully adjustable mounts and having first ‘optically centred the scope I then zero the rifle at my chosen distance by using the MOUNT adjustments and NOT the scope turrets. By taking your time, you should be able to get it fully zeroed using the mounts and may only have to adjust the scope turrets maybe 1 click maximum, hence the scope remains fully optically-centred on your rifle.

Note the elastic used to hold scope in position when rotating. 

So if you are feed up with nothing to do during this Coronavirus/Covid 19 Lockdown period, then have a go at building something like this.  When optically centred, it may just get you those extra few target points!

Please stay Isolated and Safe my shooting friends during this difficult period.