Very interesting groups. I agree that they prove nothing in particular about the difference the match primers make, but the interesting thing is that your groups get a lot better at the longer distances. At 100 yds you shot roughly .9 MOA, at 200 it was roughly .6 MOA and at 300 it was roughly .7 MOA! Hard to "blame" the scope for that. (I took the different picture sizes into account.)
If you really want to test the primers, I would suggest doing it with a blind test and at only one distance. Have a friend load the rifle without you knowing which loads you will be shooting. There is a psychological phenomenon where when you expect one thing to be better than another and you can influence it (more careful aiming, steadier hold, etc.), you subconsciously make it better whether it is or not. That might be an eye opener.