Last edited Mon Jul 1, 2013, 11:14 PM - Edit history (1)
When it is reported that the gun is dropped and went off it is going to be one of three scenarios:
1: A rifle or shotgun was dropped. They typically do not contain the internal safety features that modern handguns have. There is at least one rifle (the Remington 700) that has been accused of being prone to firing when dropped - particularly if an amateur or unprofessional gunsmith had modified the trigger.
2: It is a poorly designed modern handgun or a non-modern handgun (say pre-1980 or so).
3: The person is lying.
Generally speaking, there are two ways a gun could "go off" when dropped.
1: The gun is carried with the internal firing mechanism "cocked"; i.e. all the parts needed to fire are stored under spring pressure waiting to release. If the fall makes the internal trigger mechanism trip then the gun will fire. Guns that are designed to be carried with the firing mechanism "cocked" almost universally do have external safeties (handguns and long arms alike).
2: The gun is not carried with the internal firing mechanism "cocked", but if the gun is dropped the internal parts could move in unexpected ways due to the forces involved when it hits the ground. These are the types of guns that if "properly designed", there will be internal safeties that specifically prevent the force of hitting the ground from moving any parts related to firing.
I'll add that when I say "properly designed" I am stating my non-professional opinion. There is no national law in the United States that requires all handguns have internal safeties. Some states do have laws that effectively require this. Also, since most police and military require guns to be "drop proof" when they are procuring new weapons, pretty much any major gun maker that designs a handgun they intend to sell to military or police are going to design them to be "drop proof". The exceptions that are left are some very inexpensive handguns, and modern production of older designs. There are handguns being made and sold today that were designed over a century ago - anything designed prior to 1980 or so probably doesn't contain these features.