Just breaking the square corner off at the very top the leading edge on the stop and polishing the top of it will minimize the line. You could probably delay the stop a bit, but trying to get it to pop up quick enough from a later start and positively lock back up could be problematic during rapid fire. More spring pressure might cause it to bounce. The way it is DESIGNED to work is the reason guys like Miculek and McGivern could do what they do. If you fire 5 rounds in .5 second the cylinder has to unlock spin one chamber and positively lock back up every .1 second.

Ever notice nobody sets these rapid fire records with Colt Pythons which have a more delayed lock up?