The plunger tube is the weak link in the 1911. I recently had one come loose after 50,000 rounds. I had a new one installed (properly staked) and silver soldered in place. I don't think it will come loose again. Yours came loose a little quick, may not have been properly staked. I don't think you are doing anything to contribute to the problem. S&W makes a good gun; shoot it until something else wears out or breaks, hopefully it will be 10's of thousands of rounds from now.