I tested 4 different loads in my 300 Win Mag today. I shot 5 rounds of each load. I let my rifle cool down and cleaned it between each load variation. I noticed my gun didn't group well until rounds 3-5 after it had some fouling and warmed up a bit. I am going to try a couple of other "recipes" and my question is should I put a few through the barrel to foul it before testing. I am shooting a Remington model .700 XCR with a HS Precision aluminum bedder stock and a weaver 3X15 tactical scope with 3 bolt weaver rings and weaver pica tiny rail. The barrel is a factory Remington barrel. It just seems to group better when the barrel is fowled. this is my first semi custom expensive rig so I am learning as I go.