This happened at that wonderful Casa Grande public range we attend every so often. http://www.12news.com/story/news/local/valley/2015/11/30/girl-shooting-range-accident-recovery/76576112/ My cynical yet experienced and educated guess is this: the man shot a few rounds out of his latest pistol, a short-reset striker-fired semi-automatic. He reloaded it, chambering a round, in preparation for having it “ready for action” upon return to his glovebox or bedside table. Having (sloppily) handled D/A revolvers most of his life, he lifted the holster in one hand with its length aligned with the firing line and then, holding the pistol perpendicular to “muzzle down range”, jammed the pistol into the new holster with his finger on the trigger…negligently and recklessly endangering everybody to his side.