The exploding gun trick

This is one of Uncle Steve's favorite bits -- the cheap gun that explode in the hand of the irresponsible user, giving them instant karma and one fewer hands. I'm listening to The Drawing of the Three, and Roland (being a mary sue) causes a gun to explode by shooting it. Of course he does. Because that's just the coolest cowboy trick ever!

Over time, I can see King refining "shooting a gun and making it explode" into something more narrative and moralistic.

Has King ever spoken on this exploding gun thing? Where he picked it up from? What do you think? Do you roll your eyes when he pulls this chestnut out again?