Pistelle x68 HPA issue test

I’ve been having issues with using the long tuning chamber and HPA. After firing 1 round, the trigger would go dead. I had a hypothesis that it had something to do with the aluminum rounds. I had issues with the aluminum rounds with my TC 68 and when I switched to nylon rounds it worked just fine. Tested my hunch out and sure enough, when I fired the first 4 nylon rounds, no issues. After firing the aluminum round the issue returned. There aren’t any issues using aluminum rounds w/out the tuning chamber and HPA. It’s fine with a barrel modification. Just me learning along the way on this new journey of home safety defense. Hope this helps someone new like me that has the same issue.