Originally Posted by C.Eaton
The whole point is to make the dovetails/scope and barrel parallel. If done properly there is no zeroing afterwards as such as you're bang on for say 25-30yds anyways so your other settings should pretty much line up.
Not strictly true, it's the reticle erector tube that is being centralised within the scope housing. You need to zero the scope afterwards with packing or adjustable mounts, only using the turrets to fine tune the last click or so.