Why doesn't S&W use a systematic numbering system? For example, a number with an easily readable pattern that indicated date, type, and number?
Because that would be too easy.
My father passed away 7 years ago and we were going through some stuff in the attic and came across a Smith and Wesson 32 pistol... the serial number is 404**
Due to the confusion that can sometimes emerge when identifying old guns, we'll need some more information. I'll write this under the assumption that you don't know much about guns, pardon me if I'm wrong...
1) Does the gun have an intertwined-"S&W" logo on it, or does it only say "SMITH & WESSON" as part of the caliber designation on the barrel? If not, what other logo or lettering is on the gun?
2) Do you load and unload the gun by pressing a latch on the side, which makes the cylinder swing out to the left? This identifies a "Hand Ejector", the only type of revolver S&W has mass-produced since the 1940s.
3) If not, I assume that you load and unload the gun by squeezing two buttons on the top rear of the gun, which makes the barrel hinge down and cylinder hinge up. This type of revolver is called a "top break". OK, now that we've established it's a top break, does it have a visible hammer?
4) If so, does it have a trigger guard (loop of metal around the trigger), and does the hammer move backwards by itself when the trigger is pulled? These two features should normally coincide.
NOTE: Verify that the gun is unloaded before attempting to pull the trigger! Point it in a safe direction- at the ground is usually good- then squeeze the two buttons (or push the latch forwards), swing the cylinder up (or out to the left), and remove any cartridges from the cylinder. If the gun is the Hand Ejector variety and the cartridges won't come out readily, grasp the cylinder firmly in your left hand, point the barrel upwards, and give the rod sticking up from the cylinder a good, sharp push downwards with your right palm. That's what it's for.
Gunpowder that is kept in a cool and dry place will stay good for a long, long, LONG time. It is
NEVER safe to assume that cartridges won't go BANG just because they're really old!