The Aero Precision AR15 Buffer I would recommend is an H2 buffer MPN:APRH100284C
H1 and H2 buffers are typically used in 5.56 builds and seem to be the most reliable buffers to help the firearm function correctly. It similar with 224 Valkyrie. If you have a barrel length above 11.5 inches I would say to use the H2. If it is smaller that 11.5 inches, then go with the H3.