Originally Posted by neilL
Use a set of adjustable mounts. Adjust those so that the optically centred scope (turret centred in range) is close enough then look at the difference between front and rear mount gaps. Then get a rail made to suit. Johno did that for me some time back. Swap scopes and then you find 'zero' is just a couple of clicks up/down.
If you are centring the turrets in range this is mechanical centring not optically centring.