When I was at ATC camp in Malta (about '72) we were shooting on a range out to sea when a local boat came into view. The STOP was ordered and all cadets instructed to apply safety catches (Enfield .303). One of the cadets stood up holding his rifle then there was a loud bang and a rather scared looking cadet.
He was asked what happened; he replied he'd pointed the gun at the boat and pulled the trigger. The Oi/c examined the rifle and found that although it looked 'safe', the safety catch wasn't actually pushed all the way so it could be fired.
The round actually hit the wheelhouse of the boat and ricocheted inside it virtually demolishing it but thankfully no-one was hurt.
The station commander was 'in conference' with Dom Mintoff (the then Maltese PM who eventually kicked the military out of Malta) for several hours while the the problem was sorted out.