Have you considered the heavier M-16 full auto bolt carrier. When I put together my custom AR-15 with either a 20” or maybe it’s a 22” Kreiger match barrel, the folks at Brownell’s suggested I consider that bolt carrier to slow down the cyclic rate. I also have a JP adjustable gas block too. That has worked out well for me. When I change loads and I don’t like how it cycles, which is rarely, I just close the block until it quits cycling and open it back up again until it cycles to my satisfaction. I know an adjustable gas block isn’t cheap or easily replaced but the heavier bolt carrier is quite easy to install.