I thought I had this problem behind me after adjusting the spring tension up. On the next range trip the same thing started happening after about 15 rounds. About one round out of 3-4 it would slam fire on bolt closure thus locking up the trigger. Sometimes I could reset the bolt and it would work sometimes I had to cycle the bolt 3-4 times to get it to actually fire. My other rifles dont do this so maybe I have a bad trigger on this one. I think Ill just replace it as mentioned above.