Yes. It's hard to tell what really happened when there are so many conflicting testimonies. Some testimonies you know are just wrong either through the passage of time simply people mis-remembering and some just made up. I know a lot of people here have watched video of some of the survivors interviews. Some of those are almost cringe worthy to watch. You can tell they are just repeating myths they've come to believe themselves. As for Murdoch everything I have read about the man just doesn't jive with me that he would swallow lead. He comes off as a no nonsense guy to me. He just got dealt a bad hand by being on watch when was. I don't think anyone could have done better with what he found himself with. Some Titanic historians say if he just went hard over at full speed he would have missed the berg. Others say different. So Mr. Murdoch has generated a lot of controversy over the years. And as you have pointed out he was busy that night working the decks/boats. I don't think he even had time to stop and get depressed enough to off himself. Of course that's no proof of anything. Just my belief on it. As the youngsters say nowadays.."show me the video or it didn't happen". In other words there's no way to prove it. One of the many things about Titanic that will remain a mystery until somebody invents a time machine.Absolutely. While I am the first to admit that a lot of "events during the sinking" of the Titanic are based on collation of one or more survivor witness accounts combined with educated reconstruction, I personally have researched into the alleged 'Officer Shooting Incident' from one angle - Titanic survivor scullion John Collins. That has been discussed in some detail elsewhere but suffice to say that Collins knew Murdoch by sight (NOT personally) and always maintained (according to his daughter Mary McKee among others) that the First Officer was knocked overboard with several others when the 'wave' caused by the ships sudden downward lurch washed over those around Collapsible A. Collins himself had a child in his arms (probably one of Alma Palsson's children) but it was torn out of his grasp. Collins himself went briefly under but soon surfaced and managed to reach the overturned Collapsible B to be hauled on board.
While there might have been a shooting incident on board, the statements by various survivors are highly variable; while some sound plausible, others seem highly unlikely. There is no specific reason to point the finger at Murdoch other than some people's conjecture that he must have felt 'guilty' for not being able to avoid collision etc. But as I said before, there are statements by Collins and others that suggest strongly that Murdoch was working (presumably with Moody and perhaps McElroy) on trying to get Collapsible A into the water when they were all overcome by the flooding.
P.S...What you wrote about John Collins. His testimony pretty much coincides with what Lightoller wrote to his widow. Although I know that in itself has generated controversy but what hasn't other than Titanic sits on the ocean floor. Cheers.