Baldwin claims he didn't pull the trigger. That pretty much eliminates the 'IF' in your sentence.
And there's the rub. Baldwin says he didn't pull the trigger, HOWEVER, he also said that he was attempting to lower the hammer. And that means pulling the trigger, if the gun is in proper working order.
I cannot think of a way the gun could be broken and allow the hammer to stand at full cock (which it apparently did) and then not fall when the trigger was pulled. Even if the hammer could be pushed off or jarred off and fall, without the trigger being pulled, it still takes an action by the user to do that.
Baldwin doesn't say he did that. I fully believe that he believes he didn't pull the trigger because he doesn't remember pulling the trigger. And I think it should be fairly easy to show, in court that people who undergo severe mental or physical trauma often do not remember ALL the details of the event or what led up to it.
Accidently shooting someone would, I think, for most of us, qualify as severe mental trauma. Therefore I think its a reasonable argument to say that Baldwin did pull the trigger but thinks he didn't, and if the gun is in proper working condition (which leaked info from the FBI report says it was) then the trigger must have been pulled. However, "leaked" information is hardly reliable data. SO, we need to wait until the FBI report (the full report) is made available to the public, which won't be until its either entered into evidence in the court records, or publicly released after the trial is over.