Used 308 brass will need to trimmed, more so than, for example, 223. It does seem to stretch more. Furthermore, most of the commercially available 308/7.62 MilSpec brass available will have been fired in machine guns which tends to puff the brass out significantly; including length. This is because auto loading weapons have loose chambers by design, to ensure reliable feeding and extraction at high rates of fire. That makes the cases more difficult to resize initially, but subsequent resizing after firing in your bolt gun will not be as difficult, and hopefully you will not need to trim every time.
I do have some commercial 308/7.62 brass (R-P) which I like, and also foreign military surplus, which are reloadable if they are boxer primed. I like AFF (So. African) as it seems on par with LC and better than TAA, which for some reason, when I have a case issue, its is one of the TAA's. If you can find WW, R-P or other new commercial range brass, you are good. A lot of military surplus will have Berdan primers and can not be deprimed and reprimed on the common equipment.