Perhaps one could set up a rest / vise in such a way that you could shoulder the rifle but it is still in the vise? Either at the edge of a table or something that works at standing height? Then leave the rifle at whatever cant is produced by putting it to your shoulder as naturally as possible, then line up the scope vertical to a plumb line? I am just very new at this... I am waiting for my first scope for my first rifle, i will be doing practice and silhouette with a 455 american. I have no idea yet how much difference it will make to have a cant or not. However some members suggest, and this is strictly for silhouette shooting, that having a cant between rifle and scope reduces neck strain at matches and during long practice sessions. We shall see, i plan on experimenting with scope / rifle adjustment to find what is most comfortable and most accurate for me. Eventually i will be shooting long range target from a rest, and with that setup it will likely make the most sense to be absolutely sure the rifle and scope are adjusted to each other accurately. Also a huge thanks to the community here i have learned so much in the past few days i almost feel like i might actually hit a target on my first day out at the range. Hopefully it will be the one i am aiming at lol.