ETA that I agree with you - I have some general thoughts.
The best way to analyze the weapon choice and leg shot would NOT be asking: 1. what would the best weapon for an assassin. 2. how would the most skilled super assassin shoot someone on the street.
It would be asking: 1. what were the gunman's goals? Quiet and as un-traceable as possible. And obtainable. IMO this points to a compromise on function - as there was manual action between firing shots. He was not thrown off by that manual actions, so he either anticipated this or trained to be smooth. This weapon choice also say to me, IMO, that he was not going to shoot bystanders who tried to interviene or police if they arrived - the weapon was meant to dispatch an intended target.
2. Shoot to kill traning emphasises center mass. Gunman shot the leg first. IMO, on facts known why the legshot first is wildy specualtative without being based on much.
I don't know what I'm missing here, I have repeatedly noted the gun choice was for the silencer (the reason the gun was called the "assassins" gun in the advertisement, not stated by me, as the best gun for an assassin).
It certainly is not an assassin's gun for efficiency.
It's obivious he did a lot of dry firing and was comfortable using the gun, however I do think he looks at the gun several times. He could have been equally practiced and comfortable with another gun with a silencer.
The problem with using a single shot gun is that there is more opportunity for something to happen. If the victim had been armed, I think he
may have been able to return fire or able to run to the door. It could be that the shooter had planned on being much closer to the victim and get him down with a first shot in the back. The shooter would not have known if someone else, who could have been armed, could have stepped outside just as he first shot.
It suggests to me that he already had access to the gun he used. I could be wrong and he loves this gun and sought it out on purpose and had no idea that a different gun would have been a better choice.
As far as traceability, he choose a unique, far more traceable gun, even with the SN removed. I'm guessing they are investigating the feasability of checking import records and narrowing down the model.
He could buy any of one of the of the massed produced cheap pistols and found a silencer, on the street or under the table. add, Much harder to trace.
MOO