Can't tell you what to do with your own fingers that's your business but I've seen some pics of some seriously damaged flesh from being too close to the cylinder gap.
I've personally seen a guy holding a .357 cradled in his palm when it accidently went off, it split his skin very nasty a couple inches long seem deep, but the blackness of the wound filled with powder granules made it difficult to tell.
Emergency room, cleaning, several stiches, great deal of pain. and painful for a couple months afterward.
Better also hope that revolver isn't spitting any lead or it will be even worse.
As to the sound, well sound is a funny thing. We can measure it in detail, quantify and qualify it but the ear hears what the ear hears. And what the ear hears is different, depending on where the ear is, in relation to the sound source and reflective materials.
We can set up an experiment and measure identical rounds with and without barrel cylinder gaps, and get different values, but I'm pretty confident the naked ear won't be able to tell the difference.
Pistols and revolvers firing the same round sound different to the shooter. My experience is the carbine is a little quieter. Do you think that the longer barrel and more complete combustion of the powder, creating even more gas, and higher velocity produce less sound at the muzzle?
Or perhaps its because the muzzle is a foot + further from your ears??