Nice shooting.
KG-12 is nice, so is Wipe-out, or if you don't want a second mortgage so is janitors 10% ammonia from Ace.

As to your case question, we need a lot more info; but given your posted pics, have a pretty good idea.

Your targets show 28.7gr loads. That is a book max load. Without knowing your velocity parody from starting, you are most likely over Pressure. So if you load the Creedmoor the same way, or load as is popular on the Creedmoor board; you are well over Pressure.
So is the brass soft, or are you overloading it?

Book data NEVER list lot numbers tested, factory rifles are "looser" than SAAMI minimum spec test equipment. So you will never run the same velocity, charge for charge. And not knowing the burning rate that was tested, versus what you have.... Watch your velocity. When you either:
Catch-up to book velocities, OR exceed book velocities; you have also exceeded book Pressure.
"Signs" of Pressure typically happen North of 70-75,000 psi.