I took off my barrel to my Christensen arms ridge line to check the barrel threads because I am rebarreling it. I reinstalled barrel with proper headspace gauges and everything checked out. Went to shot it and blew a primer. I only had 5 shots loaded up, my loads are about 2950 FPS. I hooked up the chrono and shot again and blew another primer. Checked the FPS and it was 3160, and again at 3140. This is a 6.5x284 norma and that is a very high and dangerous. I checked the cases with my head space tool and they were the same size as Normal. What would cause an almost 200 FPS gain with crazy pressure?