Years back, a guy I went to school with joined the Marines. 2 years later, he was killed in a firearms-related "training accident." If it was murder, someone would have been charged, but no, someone accidentally shot him because of carelessness.
A Sergaent I know who recently retired from the Army said he'd seen a soldier shot in the back of the head because of the carelessness and disregard of another soldier.
I purchased a new pistol and showed it to my friend who was in the Marine Corps at the time. The gun I handed him was unloaded, but he did not check the chamber and waved the gun around when gesturing towards things (including me.)
Another friend, in the National Guard, was showing a group of our friends the difficulties associated with shooting a rifle while wearing body armor, using an AR-15 to demonstrate. During the course of his demonstration, the rifle was pointed (not aimed) at a man across the room. Whenever our friend turned around with the AR in hand, the muzzle went with him, at waist height, across a room full of people.
My roommate had a cousin in the Navy who was selling his S&W M&P .40 C before he shipped out. He was the type of guy who liked to dry fire the gun with his hand in front of the muzzle, and did so repetitively, irrespective of what the bullet would have hit once it went through his hand.
A friend in the Marines who recently got back from Iraq showed me several pictures and videos of his tour on his laptop. One video had him singing kareoke, and he grabbed the barrel of a loaded M-16 to use as a "microphone." The other involved a Marine pointing an unloaded M-9 at another Marine's head, dropping the slide and pulling the trigger to see if he would flinch.
Not long ago on THR, there was a case where a soldier blew his hand off because he used a live .50 BMG round as a hammer.
I am not saying that everyone in the military is careless with firearms. It has been
my experience, however, that unless an individual goes into the military with a good understanding of safety and respect for weapons, they don't develop it there. The usual response I get from someone in the military that is handling a gun carelessly is an egotistical remark that they're in the military and that because it happens all the time in the military I have nothing to worry about.
My brother, a lifelong civilian, accidentally shot his BMW in the garage...
Unfortunate, but pointing a firearm at an inanimate object that is capable of stopping a bullet, should one be discharged, is completely different than pointing a gun at a human being. A BMW is an expensive backstop, but in this case a backstop nonetheless. Compare the consequences of what your brother did with what Longhair75's brother did--they are not the same.