If we are to believe the gun was actually put on that shelf, no, I do not believe she could reach it without standing on something. Actually it is most likely just another of her fabrications to explain where the gun came from. I don't believe it was ever in the closet.
MOO
To any observer in this case JA story of running around the bathroom and bedroom including a quick detour into the closet is complete fabrication.
In her motor mouth inimitable way she described an immense amount of activity and struggle that extended to the shower stall all the way back into the shower stall with a 185lbs corpse. JA provided a running dialogue and an action packed saga of TA vs JA.
Unfortunately for JA, she has Sony camera photo time stamp that shows the length of time passing from the time the camera on the floor took a picture of the ceiling - the struggle and then less than 2 minutes later JA is dragging the corpse back into the bathroom.
Despite JA astonishing lapse of memory she did manage to plant 29 knife wounds into TA body. Shooting once to the head plus thrusting in and pulling out a knife 29 times takes up some 2 minutes. But then to grab TA and slice his throat to a point of near decapitation takes some more time.
So unless JA claims that there was a cosmic stoppage of TIME that day her story-
of running around the mulberry bush, rushing in and out of a closet, stopping to obtain a loaded gun, exiting back into the field of battle, playing football with TA and being tackled, pointing the gun, remonstrating that TA should "cease and desist" , struggling some more, discharge of gun, and then proceeding to JA state of "automatic pilot" -
is pure unadulterated cow manure.
I would imagine when confronted with the photo timeline JA will claim:
*the time stamps are incorrect or falsified
*the camera when falling did not measure time correctly
*she doesn't know why the timestamps report those numbers
Nurmi and other deluded defense lawyer commentators proudly assert that the state cannot prove JA story wrong.
In other words, for example, prove that TA's incident with little boys did NOT happen.
This is tantamount to proving a negative.
JA could have just as convincingly told the world that aliens intervened and sliced up TA .
Nurmi would have extracted the precise timeline of the alien invasion. JA would have described in excruciating detail the appearances of each alien visitor to TA bedroom.
Then Nurmi would have said "Prove that aliens did NOT intervene".
That said, a legitimately panicked person might turn the wrong corner. Or might try to get to a loaded firearm if they thought that was their only option. 
lease:
