Thanks for your advice deldriver, but when it started acting up I put a new OS Spring and was told to check the gas port by a member here that fixes and build firearms to clean it out cause it was clogged. I did with the bit he mentioned and luckily got the Black Carbon off the piston as it was marked. I put it back and used my tool to tighten it like he said. I already shot it at noon time. I check the nut when I took it down and the nut is fine and the piston is moving freely. There is still something going on, so we're going to check out another possible reason why it's doing what it's doing.