(1) The first three shots of ANY string have to be in semi-auto.
(2) In order to start ramping you have to pull the trigger at a minimum rate of 5 pulls per second, that is once every 200ms or faster.
(3) Once ramping has started you must continue to pull the trigger at a minimum rate of 5 pulls per second (once every 200ms or faster) in order to sustain ramping.
(4) Ramping stops when you do not pull the trigger for 200ms.
(5) There is NO one second ramp restart period. That means that as soon as ramping has stopped (see 4) then you have to start again at (1).
Quote from Flash > Planet Eclipse