Sorry, another gun question - although about the mechanics and safety of them and not legal issues.
Say you’re just about to discharge your firearm downrange from a proper firing stance when someone or something slams into you and you accidentally drop the weapon to the floor. Which firearms would still potentially discharge if they were dropped in this fashion and which would be perfectly safe if dropped?
The answer to this from the manufacturers would likely be that any/all guns could “potentially discharge.”
I own two pistols with factory drop safety features and both owners manuals state that while the possibility is reduced, dropping the weapon could in rare cases result in an accidental discharge.
I don’t know what the odds are exactly, and this is probably just lawyer-speak to cover them, but it’s there nonetheless.
California tests all pistols sold for safety, including drop tests. They have a list of certified models.
I’m not sure there’s a way to get an accurate number; the problem is mostly confined to older weapons (especially old single action army revolvers and some old shotgun designs). These require the hammer to be cocked before firing; it’s during that stage (hammer is cocked but the trigger hasn’t yet been pulled) when the weapon’s likely to go off if it’s dropped.
Definitely lawyer-speak. One point that my instructor stressed during my first gun-handling class is that if you should drop a modern pistol, LET IT GO! If you try to grab it, you could easily get your finger on the trigger in the process and cause an accidental discharge.
Some single-action revolvers (those without a transfer bar safety) will fire without pulling the trigger if the hammer is released by the thumb in the act of cocking it. This is a reason why early revolvers were often loaded with an empty chamber under the hammer. Some examples of the Freedom Arms model 83had a very few instances of claimed accidental discharges occurring from the hammer being released midway through it being raised, despite the presence of this type of firing pin blocking safety. When the pistol was chambered in .454 Casull…the damage was considerable.
Modern SARs incorporate a safety that prevents this from occurring. Even in the two cases I cited, it’s debateable whether it happened the way the plaintiffs’ sides claimed. The first case’s victim was under investigation for financial improprieties, and the second case’s victim may have left the pistol cocked and holstered, where debris may have pulled the trigger accidentally.
Examples of the Czech Cz-52 pistol are known for firing when activating the decocking mechanism, which is ironically intended to safely release the hammer without discharging the pistol. Can you drop the pistol in such a way as to activate the decocker?
The wiki for accidental discharges notes that Sten guns were notorious for accidentally firing when dropped. I do not know whether dropping a firearm susceptible to slam firing places enough of an inertial load on the firing pin to cause it to fire.
I have a North American Arms .22WMR mini. The gun will supposedly go off if you drop it. There are slots in between the chambers on the cylinder so that the hammer isn’t resting in a dangerous position and you don’t have to leave it on an empty chamber.
I will also give my view of what Grey Ghost is explaining;
Single action revolvers from pre 1980<> did not have a feature called a transfer bar, witch is a hammer to firing pin interface, if you will. These pre transfer bar revolvers had a safety catch feature that was to prevent the revolver from firing if the hammer slipped while in the process of cocking AS long as the trigger was not in the fire position. This safety catch was not found on revolvers for the most part pre 1900<>.
Way back in the early days of the revolver without a safety catch if the revolver was loaded in every chamber the hammer would be resting lightly on a primer(percussion cap) and if dropper, hit with a tree branch or numerous other posibilitys the revolver could fire. This is where the practice of carrying a revolver with the hammer lowered onto an empty chamber started, and the safety catch was developed.
Now a safety catch is not a safety and is so stated in some revolver instruction manuals, these revolvers should be carried still with hammer on empty chamber and the hammer Down when holstered.
Some pistoleros would carry a full loaded revolver with the hammer resting on the safety catch and in so doing might forget or miss the safety catch and more plausible not know anything about the proper use of a safety catch and not all revolver manufactures are in agreement on the use of the safety catch, and many rifles also have a safety catch that was called a “half-cock” referring to a safety position but really not a safety. Because of all the miss-understanding related to all this, enter the transfer bar. This is a passive safety inter-connector and one need not know all about safety catches and hammer down on empty chambers and all that when handling a modern day SAR. The transfer bar by design prevents discharge as long as the trigger is not held in the fire position. Therefore some manufactures ok the carrying of their product fully loaded.
I have both old and new SAR’s and also the Freedom Arms modle 83 SAR.
I have also seen a New Modle Blackhawk SAR with a B.O. Trigger return spring making the transfer bar inoperative.
I would never make a claim that any gun dropped could not fire if the chamber is loaded. But some are very much more supseptable than others.
We lost a wonderful friend and union Brother to a dropped handgun when his carry gun fell from the holster as he was climbing into his boat that was in his garage. His gun was an old style and he did know there was a great potential and payed the price. 
The Glock has three safety mechanisms on it. There’s a catch that holds the firing pin back, a sort of ‘dual’ trigger in that you have to pull in inner piece back to pull the trigger and, what is probably most relevant to this question, an metal peg that physically comes up between the firing pin and the bullet when the trigger is not being pulled.
They say, when it comes to Glocks, the bullet can’t fire without the trigger being pulled.
I really don’t think a Glock will fire by being dropped. That is, assuming it didn’t catch something on the way down and pull the trigger. But just falling and hitting the concrete, I don’t think anything is going to happen.
http://us.glock.com/technology/safe-action
From Elmer Keith’s writings in the 1970s, it’s wise to keep an empty chamber at the top where the hammer pin is located: all Colt SA Army revolvers, early model Ruger Blackhawk and Super Blackhawk, the old S&W triple-lock DA revolvers.
Most revolvers don’t have safety catches in the traditional sense (ie a catch which can be set to prevent the gun firing) at all - the notable exceptions being Singapore Police Force service revolvers and a couple of “pocket pistol” designs from the turn of the century.
I’m not sure when transfer bars became standard in “Modern” single-action revolvers (nearly all of which are basically the Colt Peacemaker anyway), but many (most?) double-action revolvers have had a mechanism in the action that prevented the firing pin from connecting with the cartridger primer unless the trigger was pulled since around the turn of the century - To pick just one example, Iver Johnson “Safety Automatic” revolvers had ads saying you could “Hammer the hammer” (ie, hit theloaded pistol’s hammer with an actual hammer!) and the gun would not fire.
I’d be interested to find out why it seems to have taken longer to get transfer-bar safeties into Single Action revolvers, though.
I know from personal experience that an M-16A1 rifle will discharge when dropped, or at least when its stock is slammed to the ground by an idiot recruit presenting arms, after he had been fooling around with live ammo and forgot he had a round in the chamber. It could have been worse - he could have lost an *important *finger.
If it weren’t true, I could see this is as an amusing gag in a comedy; I’m surprised I haven’t.
But that raises the issue of safeties on carbines, not handguns.
I find that odd. It is designed so you can buttstroke someone or drive the butt into the ground as you go prone. I’m sure the manufacturer would prefer if you did it while the safety is on but that is not always possible. That sounds like a badly maintained or faulty weapon.
Glocks are “striker-fired,” which means they have no hammer. Instead, they have a heavier firing pin which is held by a partially-compressed spring. The act of pulling the trigger pulls the striker rearward, fully compressing the striker spring. Once you reach the breakpoint, the striker is released and flies forward to strike the primer of the cartridge. With the low spring compression at “rest” and the firing pin block, it would be very difficult for a Glock (or pretty much any other striker-fired weapon) to fire when dropped.
The AR-15 platform is noted for its tendency to gunk up due to the direct impingement system. If you get enough crud in the firing pin channel, it may not retract all the way and be prone to “slam fire” i.e. the inertia of the bolt during impact can bring a chambered round in forceful contact with the firing pin, resulting in an intended discharge. Other rifles (most notably the SKS and the Ruger Mini-14) are notably also be prone to this as well, despite not being direct impingement.
As for pistols, most autoloading modern pistols have one or more internal safety devices that specifically lock the firing pin in place until the trigger is pulled to nearly the release position. This is above and beyond trigger and grip safeties or external manual safeties. Most guns manufactured before 1980 do not have thesea features, or have them in only a nascent form. I believe Sig Sauer was the first manufacturer to implement such a safety on a production firearm (the P220 in 1975) although a patent search indicates filings going back to 1970. HK also offered a drop proof system using a grip safety on the P7 series of pistols (starting production in 1976), which I still think is one of the absolute best systems as it actually rotates the entire firing assembly out of line with the chamber when the grip is not depressed. If you go through gun forums and look for alleged reports about failure of drop safeties you’ll find a lot of people repeating stories about mass failures of the Glock, S&W Sigma, et cetera, but there is no trail of litigation to back this up, and this is exactly the thing that product liability lawyers would jump right on as a class action suit.
The safety features on modern revolvers have already been discussed. I’ll just note that revolvers, despite the meme that “they can’t jamb” are relatively exposed and fragile, and I’ve personally seen more issues with defective revolvers than autoloaders, albeit none resulting in casualties (though I did know one that had a Colt Python jam in-between chambers while fully loaded, requiring the gunsmith to destructively remove the trigger group in order to extract the jammed cylinder). Some blackpowder revolvers were noted for igniting all chambers at once if not very carefully loaded; the Colt Walker is probably the best known, as alluded by Gene Hackman’s character in Unforgiven. Modern brass cartridge revolvers are not prone to this, but I have seen underloaded rounds jam in the chamber without the shooter realizing and firing the next round directly into it, usually rupturing the barrel and resulting in blowback, which is why you should always wear protective glasses. This wouldn’t happen with an autoloading pistol, as a severely underloaded round wouldn’t function the action and would at least give you some warning. This is why you should always be cautious about performing at TRB drill after failure to feed.
Stranger
When friends shoot my FAL, they complain about the long and stiff trigger pull. I explain to them, “Unlike your AR, the FAL was designed so that it could be dropped from a helicopter hovering 60 feet above the ground and not discharge. This necessitated the incorporation of a ruggedized trigger mechanism with a long and stiff trigger pull.”
Sorry sir, but you totally misunderstand what I said and apparently do not understand a pre-transfer bar revolver or as in the Freedom Arms SAR’s hammer block safety feature. The safety catch IS common to all SAR’s from 1900’s <> to 1980 <> with exception to some modern day revolvers favored by the Cowboy Shooting Sports crowd.
The safety catch I am referring to is as follows,
The hammer will have 4 positions, one being the full cock position (hammer fully back to firing position) another is the Load Position (hammer drawn back aprox. 1/2 way to allow rotating the cylinder to facilitate loading and unloading/removing empty cartridge cases) the next one is the Safety Catch (designed to catch a hammer from striking primer if the cocking thumb slips off hammer in the process of cocking before full cock)
And the last is the Fired, hammer down position (where the hammer rests after trigger is pulled and the place where an unfired cartridge is subject to almost certain discharge if hammer is struck by a unintended force)
What you are intending to describe is a firing pin block safety that is manually manipulated and something I never alluded to in my above post. I also did not include any hammer function of a Double Action Revolver and the common Rebounding feature associated to them.
A worn sear will cause a discharge like that. The weapons handed out to recruits are often older and much-used.
A WW2 British Army joke was that if you didn’t have any grenades, an equally effective way of clearing a room full of Germans was to throw in a Sten with a full magazine.
The sten would rest on its butt stock and side magazine and would spin around while spraying the room at leg height.