On July 18th 1917, near Soissons, France, U.S. Army PFC William Z. Abbott broke his hand when a round cooked off while he was trying to clear a machine gun. Ever since then, “palm up thumb out” has been the rule, and PFC Abbott remains the only human being ever to have been hurt in this way*. “Palm up, thumb out” — Part of Our Military Heritage.
On a slightly more serious note, composing this page proved to be a challenge. When this conversation actually took place, the gunner said his punchline, charged the gun with it pointed at the test fire pit, and jerked the turret about five degrees over to rub it in without actually flagging the whole FOB, as the test fire pit probably took up 30 degrees of arc from where the vehicle was stopped. Drawing this proved to be more of a challenge, because the whole point is that he did carry on with his joke all the way up to firing and that’s hard to show in a static shot. So, for the record, this is artistic license. You’ll note that I did draw his thumb under the trigger, blocking it.
Lastly, bonus points to whoever can tell me the LIN on the ammunition based on the paint on the tips of the rounds.
*The remainder of his brigade was killed in a mustard gas attack shortly after he was evacuated.