Just a pedantic note, you don't want to ream the primer pockets (i.e. you don't want to make them a larger diameter).
What you want to do is to remove the small bits of the crimp that overhang the primer pocket's mouth, which makes it difficult/impossible to get a primer started to seat without damaging it. This can be done by cutting a chamfer (a number of different inexpensive cutting tools do this), or it can be done by pushing (swaging) this matal aside to form a nicely radiused opening to the primer pocket.
The Dillon Super Swage is picky and tricky to set up correctly, but it does a good job, and it is easy to use for many (i.e. thousands) of cartridges.
If you have fewer cartridges to do (at most a thousand or two sorta thing), you'd probably be better off using one of the much cheaper cutters. If you have any more than a few dozen to do, a cordless drill, or electric screwdriver, or very slow turning drill press, can really be your friend and save your wrists.