This is beyond your regular PTSD. I actually knew someone with some of these really terrible behaviors onc...
I too know a person with this kind of dangerous behavior. He lives on the other side of my block. My whole neighborhood believed him for a while that he suffered from PTSD acquired during Desert Storm, most of us think now his problems are something else.
He is a Navy vet, with severe back problems and subsequent pain. But I learned that his injuries were not combat related, but from an accident while unloading cargo in port. Since then, he has been addicted to a wide range of pain pills.
I used to talk with him about firearms, since I have a small collection of antique weapons and he owned and practiced with more modern guns. He acquired a license for carrying concealed weapons and began bragging about that while walking his dogs.
Problems arose when he adopted a mixed German Shepherd and Rottweiler puppy. Even as a puppy, the dog seemed insanely aggressive and hard for the man to handle. The dog attacked other dogs as it grew and eventually lunged viciously at anyone, including babies in strollers. Some of those times, I witnessed the man almost lose hold of his leash. All in the neighborhood feared to dog and his owner. The man insisted he would train the dog as a comfort animal to take to nursing homes!
Finally when the dog bit one of my neighbors, the neighbor threatened to sue, at which point the dog owner reached into his coat, declaring he was going to shoot my neighbor. The man with the dog followed closely behind my neighbor all the way home, telling him to turn around and "get what he had coming."
Thanks to luck, the dog owner must have been bluffing. My neighbor pressed charges and the dog owner was served court papers to restrict his dog at home and ban the dog owner from our street. He was not further prosecuted and still lives in the neighborhood. Rumor is that he has grown even more bitter and could become yet more dangerous.
I think the man's actions are much less related to PTSD than they are caused by long-term addiction. No one I know gives a damn what his problem really is. We just don't want to see him again.