Disadvantages to a tight bullet?

Hey guys I am very new to the SML word and recently started working with my CVA that Hankins converted. I have noticed that it shot the tighter bullets better than the ones that are loose. I do have a couple chokes in my barrel I’ve been working on but the bullets i sizes that take some pressure to get down the barrel shoot fantastic. The ones that take light pressure do not shoot near as well. Am I hurting anything by keeping them tight? The tight ones shot 5 under and inch at 100 yards. Load was 275gr star tip furry and 55gr N120