what firearms could discharge if dropped?

[BobbyQuickdraw]

The Glock is highly unlikely to discharge if dropped, perhaps one of the top 2 or 3 guns in regards to safety in a drop situation.

The firing pin of the Glock is nowhere near the primer until the trigger is being pulled.

I'm no glock defender or apologist or anything, but if dropped the odds of that gun going off are likely 1 in a billion. Considering that millions of them are owned and some have probably been dropped, they seem safe so far.

That said, many handguns will not fire if dropped. And it depends on how the gun was dropped. Like was said earlier, if your gun is primed and ready to go, and you drop it, watch out. If its on safe, odds go down significantly.

The Beretta 92 on safe can be dropped, kicked, and tossed without it going off. Don't do it that though, because there is that 1 in a billion chance.

 

[mljdeckard]

Keep in mind, that while MANY firearms (NOT just Glocks) have very redundant safety features, and under MOST imagineable circumstances will not go off if dropped, remember that the primers themselves are impact-activated objects, and it is to say the least, disengenuous to make broad claims about infalability.

I did witness more than one (very old and worn) M-16 A1 discharge when the butt struck the ground hard, with one hand on the forearm and the other holding the stock.

 

[Geronimo45]

The Glock is highly unlikely to discharge if dropped, perhaps one of the top 2 or 3 guns in regards to safety in a drop situation.

Yup. Matter of fact, I think the majority of the safeties exist to avoid the gun going off if dropped.
Revolvers have incorporated similar safety features for many decades. I seem to recall an ancient Iver Johnson ad, where they advertised how safe their gun was: "Hammer on the hammer!" was the tagline. You could beat on the gun's hammer with a real hammer and it wouldn't go off. I think that dated from 1920s or '30s, but it could've been the '50s.

 

[Cosmoline]

I did witness more than one (very old and worn) M-16 A1 discharge when the butt struck the ground hard, with one hand on the forearm and the other holding the stock.

I've never heard that the AR was drop safe. Most rifles are not in fact drop safe. Which is one reason I like my Mosins. A 20 lb. latch that locks the pin and half of the bolt directly to the receiver is about as safe as long guns come.

 

[KBintheSLC]

Most SAO's are prone to this if there is no internal firing pin safety. My 870 12ga can fire if it is racked and dropped... even if the safety is on.

 

[Roswell 1847]

A friend died from a staph infection of a wound received when his .22 double barrel Remington style derringer replica went off when it slipped from a jacket pocket and landed hammer first on the bottom of his boat when he reached for his tackle box.

In tests Remington style double barrel Derringers went off about 80% of the time when dropped no matter which way you held it before releasing it.
The heavy curved butt directs the hammer spur to the surface it hits as if designed to do so.

Early production M1 Carbines could rack a round into the chamber and fire it if dropped hard enough on the butt. Like Blowback Sub guns the operating rod/slide has enough weight that intertia can cycle the action.
This could happen when jumping down from a truck or in parachute openings or landings with a magazine in place.

Later production M1 carbines have a slight "Knuckle" cut in the right hand locking recess and bolt lug. This produces just enough hesitation to prevent the bolt from flying open under its own inertia.
Unfortunately .30 Carbine ammo is often a hair longer than it should be and some times stretches when fired, this can lock the action tight enough that you have to kick the operating handle with your heel to eject the empty.
Fired Cases I've examined from a Carbine that consistently jammed in this manner revealed that one in six were exactly .006 longer than the rest, these were the cases that locked up the action.
After carefully polishing down the knuckle in the righthand locking recess to about half its former protrubence, used a white arkansas stone, the gun functioned properly.

 

[Jim March]

I'll discuss revolvers as that's what I know best.

The Ruger transfer bar system actually pre-dates Ruger - I think Iver Johnson first played with it. It is VERY safe as stated already...I believe it to be the most drop-safe design going today, esp. in guns that don't have a manual operated safety.

Transfer bars have one downside: because there's an extra piece of metal in the ignition cycle, friction goes up and the mainspring needs to be about 25% heavier on average. So trigger feel sometimes suffers fractionally.

Transfer bar safeties are used in many recent-model S&W and Taurus guns, all Charter/Charter Arms/Charco/Charter2000 centerfire guns (and the rimfires except for their "Dixie Derringer"), the Freedom Arms model 97 series, the Beretta "Stampede" series (incl. "Marshall" and "Bisley") and many more.

The alternative is the hammer block - a system that blocks the hammer from forward travel unless the trigger is pulled removing the block. The key difference is that if the hammer block breaks, the gun is a "zero safety" functional weapon. If a transfer bar breaks, the gun is a doorstop. Also, the hammer block travels in a channel in most designs that can get "gunked up", blocking it's functionality and decreasing the safety of the gun considerably.

20th century Colt DA revolvers (Police Positive, Python, Dick Special and more) had well-executed hammer blocks that I would trust fully loaded so long as I'd checked the functionality of the safety (more on that in a sec).

Pre-WW2 S&W DA revolvers had a hammer block that *usually* worked, but the design was re-vamped late in the war. I do not recommending using pre-WW2 S&Ws as CCW guns. Post-WW2 hammer-block DA S&Ws are as safe as any Colt DA and I would trust those six-up - again, as long as I'd tested the gun before buying and as the last step in any cleaning session.

TO TEST A REVOLVER SAFETY (any centerfire at least):

With the gun UNLOADED (check it again!), cock the gun and point it barrel-up in a safe direction and drop a pencil down the barrel - either a flat-face unsharpened nose or the rubber eraser end as long as that's flat too. Or a similar dowel rod.

Holding the hammer, pull the trigger and ease the hammer forward a bit, then with your finger OFF the trigger completely let the hammer snap forward. The pencil shouldn't jump. Now pull the pencil, cock it, put the pencil back in, raise the barrel and dry fire the gun - the firing pin should bounce the pencil out a foot or to, a yard at the most (kinda neat). The pencil won't achieve a dangerous speed but don't point it anybody's eyes.

This tells you that the gun CAN fire, but also that with no trigger pull there's no primer contact possible. The same process works for hammer block or transfer bar guns.

Sometimes you can ditch the pencil and just look at the firing pin action with finger on and off the trigger looking sideways through the gun at the rear of the cylinder. But if it's a tight action (early "recessed chambers" or the Freedom Arms guns) it may be hard to spot - the pencil will always tell the tale.

 

[sailortoo]

Drop safe

An odd ball, in a way, but a totally different approach to "drop safe" from those already discussed. My "hide away" (not regular carry) is a NAA Black Widow .22 mag., that has a firing pin notch between each chamber. Because the firing pin is locked between rounds, there is nothing to contact the rim of any rounds, regardless of the blow to the hammer, or gun in general. A truly basic, and if properly engaged, nearly fool proof safety, and no "extra" mechanical parts to move or engage or break. I've tried to imagine some way to discharge this gun, other than single action cock and pull the trigger. Obviously it is in a danger condition once it is cocked.
sailortoo

 

[Halo is for Kids]

Walther PPK decocked with the safety off. Allot of'em are carried that way.