941.20 Endangering safety by use of dangerous weapon.
(1) Whoever does any of the following is guilty of a Class A misdemeanor:
(a) Endangers another's safety by the negligent operation or handling of a dangerous weapon;
Negligent is only one part of the crime one has to meet all aspects of it to be in violation.
noun: handling; plural noun: handlings
the act of taking or holding something in the hands
Thus he was handling his coat with a gun in its pocket
the fact or condition of functioning or being active.
"the construction and operation of power stations"
synonyms: functioning, working, running, performance, action More
"the slide bars ensure smooth operation"
an active process; a discharge of a function.
So tell me how he was handling or how was he operating the gun.