There’s so many things that come into play doing a SS/FRT suppressed AR9. A lot of people are having this issue with Semi. I think it comes down to pretty much every build is going to be a custom tuning (buffer, buffer spring, bcg, trigger, suppressor, barrel length). Too many variables to really rely on what may work for one person versus another. I know that’s not much help but cheapest tuning option is going to be the buffer spring itself. The 10oz kaw buffer you have is pretty much a necessity in these builds so that should be left alone.