[Brian Pfleuger]

Apparently, when he went through the brush, he caught the hammer on some brush and cocked it, then while going through another bunch of saplings and brush, some how managed to have the trigger pulled. (He swore up and down that he neither carried the weapon cocked, nor did he touch the trigger.) If what he said was true, then he had a very unsafe holster.

It would seem more likely that it was a single event, IMO. A branch/vine/twig snagged the hammer and drew it back far enough to ignite the primer on dropping but not far enough to stay cocked. A very unsafe holster, either way.