Below not to be taken to seriously, just chat'n.
So you say your M4 jammed on the second magazine. Well being one who always looks at the glass as being half full. That would mean that you were at least able to send 30 high velocity slugs downrange before having to clear a malfunction. Which I would assume takes about the same time as it does to tactically reload a 6 shot SRH. I would also assume that you were able to fire the 30 rounds in about the same time as you would have been able to fire 6 .44 magnums.
So class in which example did you actually send more terminal energy downrange....a) 30 .223's or b) 6 .44 magnums. #2 How many more opportunities to hit something existed by firing the .223's.....a) 0, b) 1, c) 6, d) 24
The point of a .357 over a .44 mag is recoil recovery time, weight of weapon, easier ability to fire accurately one handed while peering out from behind a tree or boulder or security guard while still retaining excessive knock-down energy of a proven man stopping handgun caliber as I have already pointed out. You do not need overkill but a high probability accurate hit.
The 6" KC should be on your person not the guards. You need to now pace off 100 meters (or have the guard or one of the wives do it) uphill, downhill etc..., tack up some targets and see what you can hit from various shooting positions with the SRH and KC in rapid fire exercises.
I think you will soon discover why you should be shooting the 6" .357 with a full powered 125 - 140 grain load. Keeping in mind that only hits count.
This whole ideal of terminal energy needing to be the maximum available is wrong as your adversaries are not Elk but skinny little Patel's.
Homework -
http://www.hornady.com/story.php?s=760
A Hornady flextip 140grain .357 @ 100yds hits with 406 ft/lbs of energy @ 1143 fps. I think that will more than get the job done. Also note 100 yd/meter zeroed sites
Last comment/opinion..... The S&W 500 or even 460 is not a personal defense weapon. Its a toy (great toy) for people with more money than brains (count me in) or as Freud would ask do you think you are over compensating due to the lack of something else? You need to fight light and fast and be able to hit hard and often.