For those who say a 686 is uncarryable, has slow follow up shots or has too much flash - have you ever carried one, shot it rapid fire or shot one in low light? I have done all of these (as I frequently carry my 3" 686 or 4" Rhino, both in .357) and neither is a big deal to me. Follow up shots might have been hard at first but, like anything else, practice practice practice. .357mag is a potent round, but it's not like a .44mag or bigger. .38 Special, .44 Special and .45ACP are also fine choices if that's what you prefer.
As far as the external ballistics, faster, lighter bullets tend to penetrate more but also fragment more after they first hit something. So you will be more likely to pentrate a BG's heavy clothing (or body parts) but less likely to retain lethal force after hitting drywall. You can google this but 125 grain .357 Magnum will penetrate about 16 inches of ballistic gel. .38 special is closer to 11. In general .357 magnum will penetrate a BG more reliably than .38 special, 9mm para, .44 special or .45ACP. It is faster than all those rounds.
As far as the external ballistics, faster, lighter bullets tend to penetrate more but also fragment more after they first hit something. So you will be more likely to pentrate a BG's heavy clothing (or body parts) but less likely to retain lethal force after hitting drywall. You can google this but 125 grain .357 Magnum will penetrate about 16 inches of ballistic gel. .38 special is closer to 11. In general .357 magnum will penetrate a BG more reliably than .38 special, 9mm para, .44 special or .45ACP. It is faster than all those rounds.