Isn't the FPS limitation intended to prevent injury?
This is simple physics and I guess 99% of ASC users figured this out but... the energy output on the bb is (relatively) always the same even if the bb is heavier, meaning the slower .43 BB will hurt as much as the .20 BB that goes faster if it's shot from the same airsoft.
Isn't it why FPS are measured using .20 BBs before games even though you're using other size?
In other words, if your airsoft shots too fast, it's not the bb you have to change. Correct me if I'm wrong there.