The powder will stay dry a long time, and modern caps will last a long time. Primers in metallic cartridges made in the 1880s still function flawlessly. Even intact rounds from "custers last stand" site still fired perfectly in original guns. And the powder will last, theres the fact that a famous historical figure left a pistol loaded in a shed rood for over a hundred years and it fired fine.
True theres a chance that a cap may not function properly or a load of powder will somehow fail to ignite, but that can be prevented with reasonable means.
Powder attracts water, does not matter if its a loose powder or a pellet. A change in temperature around metal normally makes it condense, cold metal from fridge to outside in warm weather makes the metal sweat real fast. And that applies to all firearms.
To control temp changes you could take a small metal/plastic/wood box that the gun can fit into and make sure the lid has no gaps when closed and fill the inside with high strength dessicant pads. Keep the loaded gun in the box until its needed.
Some will say that a bp revolver is useless for anything other than shooting targets, but these were being used to kill buffalo, quite often with single shots. and many people have hunted deer and hogs with them with very good results, so that disproves them as being weak weapons.
Semi-autos seem to be nice as they have large capacity magazines and rapid fire but they have problems. They have at least two safeties, and most makers seem to be designing them with at least 3 seperate safties that need to be pushed to get a shot off, a bp revolver is simple, load, cock, aim, pull trigger, and repeat. And most people forget safeties when someone is trying to kill them. Double action revolvers were foudn to be the easiest for everyone to use, no safeties to push in, just aim and pull the trigger.
And a 9mm may seem wonderful because you can get lots of ammo rather cheaply, but performance wise it sucks. the only reason its considered to be a good gun is because the mauser and luger pistols used it, good gun equals good ammo to the "professionals". My grandfather was a long time cop and he learned time and again that a 38 special and 357 magnums will drop a person with 1 shot when using the old police load, aka "chicago load". If you watch american tv shows youll see the police ones where a cop puts 14 rounds of 9mm into a suspect, and the suspect proceeds to walk the 10 feet to the cop and beat the manure out of the cop..
So that dragoon will not leave you underpowered. just HIT your target, and DO NOT AIM TO "INJURE" OR "INCAPACITATE". That defeats the purpose of a gun and defending yourself. If you cant shoot to kill, no gun will be effective for defense.
