Almost one year ago, I had a CATO with a Cesaroni J595 motor, see https://www.rocketryforum.com/threads/cesaroni-j595-6xl-38mm-plastic-aft-closure-failure.146262/ Cesaroni's warranty service is not great, I did not get a replacement motor until March. Today I tried to launch it. It was another CATO, very similar to last year. Apparently the plastic rear closure blew out again. There was a loud boom right at ignition, and the grains fell out the bottom. Unlike last year, when the casing flew forward inside the rocket and damaged the av-bay, this time the casing came out the back. The chute ejected, although the ejection charge did not go off. The CATO did more damage than it originally seemed. The rocket itself is undamaged. However, the 54mm to 38mm Aeropack adapter is damaged, don't think it can be used again. The Cesaroni 6XL casing looks OK but I'm not sure if the threads are all good, I'd be nervous about using the case again. Worst of all, the 54mm Aeropack retainer, which was epoxied with JB Weld to the rocket, blew off, along with the screw on retainer cap. We were unable to locate either the retainer or the cap. Any thoughts? We found the rear closure and the first thought from the local expert was that the O ring was missing and that caused the CATO. Compare the below picture of the closure with the photo of the closure in last year's thread, that also is missing the O ring. I'm fairly sure I saw the O ring when assembling the motor, is it possible it disintegrated or blew off? Low quality video of the CATO at .