Jon, I think I disagree with your last paragraph. With the possible exception of a semiautomatic rifle (which was perceived as not very useful), everything he used was more easily available in 1970 than it is now. I owned a semiautomatic .45 handgun when I was a teenager. Shotguns were in every home. In highschool, some friends and I bought a case of dynamite and 200 pounds of ANFO, and went out to blow holes in the desert. No one questioned it. And, no one ever dreamed that you would use that stuff to hurt anyone.
I suspect more that your first paragraph holds the key. That and the instant availability of news which is now parsed every possible way to lure readership.
