so many variables
the change of point of impact while a worry may just be you
i would try a few more types of bullets,it can't hurt, the buff river groups are not that bad, looks like you pulled a couple in the bottom one
get some snap caps and get someone to load them at random for you,you will soon find out if you have a flinch. if you have creep in your trigger get it fixed and if its heavy, lighten it up at the same time,,it should break clean and crisp. use a rest or bags and pretty much try and do the same thing each time you pull the trigger
oh and save your brass,even if you never reload you can always sell them or give them away