At the last event the marshalls were given unlimited time to find bounce, they could hold the marker in any position and do anything to find bounce.
Their definition of bounce is that if you can ever make it fire two shots in quick succession then its illegal. This includes holding your finger next to the trigger (without holding the gun with that hand) and causing the vibration of the gun to let of an extra shot. This can be done with ANY electro marker, it just depends how good you are at finding the switch point of the trigger and how hard you try.
Really with this procedure there is no trigger modification you can do to prevent failing the test (short of springing the trigger so hard you can barely pull it). If the marshall is good at finding the spot, he will do.
All you can do is cap your rof.
I think a marker capped at 6-8 bps
should never fail this test.