Depends on which side of the gun you are on. I remember maybe thirty years ago, a guy tried to execute a cop in Mobile, Alabama. He pulled the trigger six times on a .357 magnum and got no shots.
Somehow they got the guy into custody and checked the gun. All six primers were dented. Just not quite enough force to ignite them. I bet the cop considered himself a little lucky.
If that cop wasn't a believer before I'll bet he was after. Weak hammer springs aren't a widely known problem.