I have tried about every Buffer combo. 5.4 colt, Vltor A5H4, Heavy buffer 8.0 and a hydraulic buffer. Standard spring weights, extra power, 308. I have full autos and simi autos. 7inch, 10.5 inch and 16. From my experience I would go with a hydraulic buffer with standard weight spring or an extra power. Hydraulic buffer is noticeable softer. Very noticeable. Pic is of my Colt RO633 DOE. C0C9275D-14C6-4CE7-8DBA-120322E602E6.jpgC0C9275D-14C6-4CE7-8DBA-120322E602E6.jpg