You should never point a gun at someone.
Daryl just bought a rifle and is showing it off to his brother Bob.
Daryl wants to show off to Bob.
Daryl shows Bob the beauty of the rifle, but says how important it is to treat it with respect.
Daryl pretends he's a character in a western film and aims it at Bob.
Daryl feels like a responsible rifle owner, and he got to teach Bob a valuable lesson.
The rifle accidentally discharges and Bob gets shot in the arm and now Daryl feels awful.