Ok today I shot a little bit down by the river on the sandbar. I shot about 25 rounds. My load is 44g of varget 175 SMK winchester cases federal match primers, COAL of 2.930 thats about .015 off my lands. 2564 fps. I had my rounds divided into two sections tumbled and non tumbled.Load data was the exact same! The reason for this is I wanted to see if there was a accuracy improvement over clean brass. What I seen shocked me and im still puzzled! I shot into 3 shot groups and the non tumbled brass with my load shot from 0.190-0.326 at 100 yards.Safe to say my average is around .25 moa give or take a little. The brass that i tumbled that has the absolute same load grouped 0.542-0.711. All the cases was trimmed to the same length and preped the same. I ran the one set of cases through the tumbler AFTER they were resized, trimmed, reamed ect. I made sure I got all of the stuff out of the case lol so thats not it. I did notice that the tumbler only cleaned the outside of the cases, the inside was still black. Anyone know whats going on?