I've been playing with this on a hammerless S&W. Basically the earlier lockup occurs before hammer release the easier it is to look at full lockup. It takes a strong finger but if I'm careful I've found that I can hear full lockup before hammer release and then carefully, this takes a strong finger hold the trigger at lockup and then examine it.
Not as easy as on a revolver with a hammer but still theoretically possible unless the lockup is so close to the hammer release that you are unable to hold it.
I think this also relates to timing problems caused by a bad trigger job. The smith has removed so much metal that the hammer falls before full lockup has occured by sufficient trigger travel.
The only thing I don't see mentioned is the advice I've heard to examine the extractor, make sure that it is lining up with the chambers properly and that the edges are sharp and undamaged. Others have reported of damaged extractors.
Great post very informative, and useful for those of use getting into playing with revolvers.
Actually, looking at an exploded parts diagram of a S&W revolver is frightening, little parts, little springs, Arghh!
Makes a Glock pistol appear a paragon of simplicity. Would be interesting to know which springs tend to wear out over time and should be replaced.
A friend had an inexpensive revolver, can't remember the name and trigger reset spring broke. Forcing you to have to manually reset the trigger after each shot, this substantially reduces the rate of fire.