I'm kind of in the same boat as your OP.
Bartlein barrel 20'', rifle gas, 22.0 gr of 8208, cci450, Thunderbeast ultra 7 in .223 direct thread.
I have a SLR AGB tuned to perfection.
Running a Geissele H1 buffer/braided spring combo.
Only thing I can think of is to add weight to my buffer...