Different bullet profiles, lengths, weight, softness/hardness, base, tip, and jacket thickness (also relative to the softness/hardness), are what makes some rifles like one bullet or another. How they conform to the rifling. Not all rifles are unusually picky, but lord there are some, and I have had my share of them, that just will not shoot anything but ONE bullet worth a tinkers damn. I've had rifles (still have 2 of them) that group worse than a shotgun pattern at 50 yards with one bullet/load but either a seating or bullet change or powder variation and they tighten up to well under an inch at 100!