Doesn't look like him. Super convenient that the gun can't be traced so we just have to trust the cops that it really was his, and that he was just out walking around with the gun and a manifesto, just days after, when anyone would be lying low?? Not buying it.
There is a world where this guy is mentally ill - schizophrenia for example - and this is yet another example of the mentally ill falling through the gaping cracks in the US health care system.
To not dispose of the weapon or the fake ID, and continue wearing the same clothes suggests irrational behaviour.
Unfortunately the US legal system only seemingly regards mental ill health as a defense if you're very rich and lawyered up.
News is saying his family is very wealthy. They own country clubs, health care facilities and real estate companies. And his cousin is a state delegate in Maryland. He also graduated from Ivy League college.
A barrel is a barrel, and I think it highly unlikely that a mass-produced product leaving a unique fingerprint on something that's been smushed into a completely different shape can be used as forensic evidence. Unless you know of it being scientifically proven, it is the domain of TV CSI.