Not "intent to kill";
That's a stupid simplification.
Intent to commit an action with the known plausible outcome of death, is murder, as soon as it has that outcome.
Why?
Because you knew you would risk it and you did it anyways.
If it's the first or second or third priority, or just something that happened on the way doesn't make any difference.
For example:
If someone shoots a gun in a shooting range, though someone is in the way to the target thus killing him, it's a coldblooded act that lead to his death in a causal matter the shooter was aware of.
There is no real difference if the person was in the way of a target, or in the way to a football (Oh dear, soccer ball of course).
I simply said that it would make court. There is nothing else I want to prove here, because a lot of it depends on the state, precedence cases, etc.
Concerning your example however: It's not an unloaded gun to begin with, if the intent was causally directed to use potentially deadly force, just not against a person, but an object (which is out of dispute as the outcome in our speculative case was death); Your example missed the point.
(@gut feeling:
Yes I appealed to your common sense. Why? Because it's relevant. The way you point it out any murder could have been an accident, as you leave the act of an aware killing out of the focus and rather concern yourself with circumstantial matters.
If it's only murder if you find physical evidence of preparation, it would be extremely easy to get off. If the weapon was in place beforehand and you can't gather any circumstantial burden of prove, the state would let the person walk, even if there are eye witnesses, which makes trailing for murder impossible for the prosecution and anyone would get convicted with a low sentence at best.)
~+~
I have a couple of more things to say on the gun example though:
Something pretty similar actually happened to me once.
I was lying in an improvised emplacement, together with a fellow recruit in basic training, securing our convoy, whilst it had to put on catenae. Finally we got the order to prepare to move within 10 minutes. We kept scanning the sector for the time and than went to move out rather casually, however, I had noticed that my buddy had loaded the gun when lying down and not unloaded it when getting up, so I told him about that.
His reaction was to kneel up, hold the ejector of the gun closely to my ear and fire it.
He said he though it hadn't been loaded.
(I fought hard, to beat my anger that time, really hard, but instead of giving him a trashing, I kept my cool. Saying not a word, I went of to report to the nearest officer, that I couldn't hear anything for now and needed to see a medic. To my great luck there was no permanent damages to my ears.)
Though practice ammunition was used, had he pointed at my face or stomach, I would be glad to be alive now, though definitely terribly mutilated.
What a terrible accident would that have been, you might point out.
I would say, that there is nothing accidental about holding a gun towards a person and pulling it's trigger.
I would also not like to see my killer getting of so easily as he probably would have, because of it having been an "accident" caused by his stupidity.
That does not really run in line with him being a danger to society, so I would swallow my pride, were that still possible, but those who make a living out of playing a sport so aggressively, often targeting other players as a cowardly effort to defeat their superiority, are a consistent danger to all the other innocent players.