Country1911 has given some great advice on reloading. I wholeheartedly agree that a single stage is best for rifle rounds if you're trying to squeeze the utmost of accuracy out of your rounds. They're also my suggestion for those new to reloading. Much easier to learn on a single stage than a progressive.
That being said, once you've got the experience, a good progressive press can churn out a LOT of very high quality rounds in very short order. The biggest variable in reloading is the powder charge. Just using round numbers, assume you're using 5 grains of powder in your pistol rounds and 50 grains of powder in your rifle rounds. If your powder dispenser varies by up to .5 grains, that's a 10% error in your pistol rounds but only a 1% error in your rifle rounds. In other words, it won't have as much of an affect on the rifle rounds. Bottom line is, don't be afraid to use a high quality progressive press to build rifle rounds, especially if you're shooting a semi-auto which goes through ammo like shit through a goose.
Last bit of advice for now; when you're in the development phase of building ammo, only change one component at a time. Want to try a new powder, different ammount of powder or different bullet? Change ONE, not all. Once you've wrung the most accuracy out of that one component, then you can change another and see how it works. And like has been said, keep a written record of all variables, including the group size(s) shot with that load.