You need a chrono to verify, but CS1983’s suggestion should give you a good idea. If both rifles have the same drop using the same ammo, then the difference is likely from a difference in velocity and BCs in the two ammo types. I have some rifles with the same chambering and barrel length that shoot 100+ fps different with the exact same ammo. The difference comes from a difference in the tightness of the chamber and/or rifling between the two rifles.