Perfect. This is what I was thinking.
Can you please go into further detail on the MOA rails and how they work please?
They simply "tilt" the scope downward, tilting the barrel upward in relation to the scope center. This raises your point of impact. Sighted in at short range you will be adjusted further towards the top of your adjustment range. This gives you additional elevation adjustment for shooting at longer distances. Obviously the further you shoot, the more the bullet drops. Adjusting for this drop at a certain distance you will reach the limit of your elevation travel and no longer be able to dial up. A canted base extends that point. The amount of cant will be advertised by the manufacturer. 20 moa is most common. This will raise your point of impact by 20 moa. So 20" @ 100 yds, 200" @ 1000 yds etc. That is a sizeable amount and will increase the range you can adjust your scope too by a good amount.
I understand that once sighted in my dials will not be centred / at zero. I was just thinking that you would want them there to start so you had the same amount of adjustment both ways when sighting in. Correct?
Not necessarily, the chips will fall where they may as it were. Depending on the type of rifle I use 1 of 2 sight in methods that don't need any specific starting point. For a bolt action that I can look down the bore from behind the rifle I'll set the rifle up on sandbags and remove the bolt. I'll look down the bore and center my target in the view through the bore. Target is at 100 yds. Then without moving the rifle I'll get behind the scope and see where the crosshairs are sitting. I'll make adjustments until the crosshairs are centered on the target with the target centered in the bore. First round is always within a few inches of center. A quick adjustment and the rifle is sighted in. If I can't view through the bore I'll start at 25 yds, fire a couple rounds and adjust a few inches high of center then move out to a longer distance and fine tune. Neither method benefits from centering the turrets. There's enough misalignment to need some adjustment anyways, and both methods don't waste much ammo if done with care. But of course everyone has their own way of sighting in so find what works for you. Just don't forget to have fun along the way!