Hex bolt zip gun - GIF

[schuylergrace]

So, does the nut do anything on it, other than disguise the joint between the threaded end and the smooth shank? Maybe, it's a jam nut to keep the two halves from rattling apart as you carry it? And I wonder (while I'm wondering about the above) how many guys, carrying these things around in their pockets, have had their bolts blow their nuts off? It had to be asked.