I'm glad to see this subject come up, it should cause all of us to take an extra moment to THINK about what we are doing, whether it be afield or at the club.
Makes me wish to say thank you, Bagfinger, for bringing it up and thank you, Jerry, for your dedication to teaching your many students.
The 'vehicle' in old grease evaporates leaving hard crud, A M12 will slam fire by design if the trigger is held down, not opening many doubles fully might cause the aforementioned discharging on closing; worn parts, sticky firing pins and other potential problems might contribute to an unintended discahrge, HOWEVER if the muzzle is pointed in a safe direction none will be harmed!
No sermon here, I simply enjoy the dialogue on the BBS and wish it to continue. Age, health & happenstance rob us of enough friends & loved ones, thank you .. lets not have our passions contribute through a moment's inattention. We should all practice & share a bit o' the wisdom stated above by others w/our friends .. you'll never know if it has the desired effect, because none become a statistic .. its the best conundrum possible with teaching safety effectively.