Oregon has background checks for private sales.  Oregon has laws about crazy people and guns.   

The killings in Umpqua Community College were not prevented by those laws nor even would have been by any of the others you are suggesting.

  

The shooter in Nevada was in legal possession of those guns.  He hadn't been found too crazy to own one or been convicted of a crime so he couldn't own one, didn't have any 'silencers' and as a retired reasonably well off elderly citizen about like your next door neighbor, gave no indication that he would wind up as a mass killer.  


"Two Nevada gun shops confirmed Monday that they sold firearms to Mandalay Bay shooter Stephen Paddock in the last year and said he passed all required background checks." "All state and federal laws were followed and an FBI background check took place and was passed by the buyer." 

He was a landlord; maybe that is what drove him crazy!


The urge 'to do something', anything, after a tragedy is just knee-jerking.