I am shooting a 300 rum, and shooting 93 grains of 7828ssc, 200 grain nos accubond. 3300 fps, <1" groups. Everything is going well, on about every 6th bullet I am seeing extractor marks, very light. Shot about 15 rounds through it on Saturday, on the 16th round the empty case got stuck??? Pulled the bolt back and the brass stayed?? Any suggestions on what caused this. Using Remington brass. Thanks, Don.