So far my only experience with reloading is for handguns, so please excuse my possibly lame questions. I got all that I need to start reloading for my new Savage in .308. Something is quite confusing through...

If I take any of my once fired cases and deprime it only, it chambers perfectly (to be expected), and I can seat a bullet without any problems. Does this mean that it doesn't need sizing? It looks like if I trim them, they are ready to go. Can that be right? No sizing at all?

I was thinking of only neck expanding with a Lyman M, but if I can seat the bullet easily do I even need to to that...? Somehow I can't believe that they need no prep...