Recently read about testing rifles with factory ammo, and you should expect as has already been said, that you may need to test a number of brands/styles. Might not happen IF you are lucky?
?..
Kind of like with a .22 rimfire where you are at the mercy of the ammo manufacture and must test your rifle with "their" ammo until you find the one which shoots best.
The biggest potential I see for problems is #1 cost for testing a bunch of factory ammo, #2 you end up with a bunch of odd ball brass should you wish to reload, and #3 you are at the mercy of the factory as per changes to their components and loads.
Box may look the same, but
??.
The best thing you have going for you is, ammo companies are more concerned about the quality of their better products then they were years back, and for that, you can thank reloaders.
Keep em coming!
CDOC