As for what causes a chain fire or what end of the cylinder it originates no one knows. This has been a controversy for years.
When Colt sold there revolvers the instructions were as follows or close to it:
Load camber with powder leaving enough room for the ball, compress ball on powder and cap the cone(nipple). It also discouraged people from using wad or fillers.
Keeping this in mind I just did a test using a new .36 , 1851 Colt/Navy replica and loaded and shot as follows. No wad, no pill, no grease over ball and the chamber was filled allowing enough room for the ball. In this revolver that was 25 gr. of Pyrodex P and a .380 casted ball compressed on top.
After firing over 1000 rounds and in fact it is now closer to 1200 we did not have one chain fire, cleaning was not any harder and we could not tell any difference in the superb accuracy we got with this revolver.
Mec (Mike Cumpston) has tried this also using his Navy 60 I believe and he has found the same results as I have , no chain fires and fouling is no worse and clean up just as easy.
In no way am I saying that it can't happen but I feel you will minimize that by making sure you have a very tight fitting ball or Conical and tight fitting caps.
It's nice not to have to mess with the grease all over your holster and hands.
I do still grease the internals and the cylinder pin and hand slot.
Here is a link to more info on our testing.
http://www.thefiringline.com/forums/showthread.php?t=202214