300BLK Ammo + Buffer Combos

[Curh]

I am running a 9inch Ballistic Advantage Modern Pistol Length BBL both suppressed and unsuppressed. I am trying to play with spring/buffer/ammo combos to get the widest range of ammo to work.
My default setup is a ST-T1 buffer with SpringCo White spring.
UnSuppressed it ran 108gr Hornady and 123gr Magtech Supers no issue. 220gr Rem shot fine but didnt locked back on last round. 208gr Hornady didnt feed well nor lock back.
Suppressed it ran the 108gr and 123gr supers no issue, as well as the 220gr no issue. The 208gr didnt lock back.

I switched to a ST-T3 buffer and it was the same results except the 208gr shot better but still didnt lock back.

I also have a Red Spring (dont think that makes sense) and a ST-T2 buffer on hand. I also am considering a white-hot spring.

Any other thoughts on what to adjust or try? Ideally I would like to find at least one sub that has no issues suppressed or unsuppressed and can handle a super on that same setup.