Same thing happened to me. Both spring & plunger rod fell out (much to my surprise!). Luckily I found them both. The next time I disassembled it I did it in the tub/shower stall with the drain closed and the area enclosed. Eventually logic won out and I figured that I needed to take the screw, spring & plunger out right after taking the grips off and putting them back in AFTER getting the hammer & hand in (as was stated by Kadmos). Obviously it is a superior design but had me scared to touch them for a while. Now I feel like an old pro but not without a lot of aformentioned angst and at least one "Oh s**t!".
With over 15 perCUSSIN' revolvers, I've been called the Imelda Marcos of cap & ball.
SASS#3302 (Life), SASS Regulator, NRA (Life), DGB#129
Wolverton Mtn. Peacekeepers (WA), former Orygun Cowboy (Ranger, Posse from Hell)