Are floating firing pins safe?

[AndrewWiggin]

I watched a video where the guy was recommending that people keep their home defense weapon in cruiser ready because he was worried that the gun could fire if dropped. Can a floating firing pin set off a primer from the inertia caused by an accidental drop? Is cruiser ready stupid?



https://www.youtube.com/watch?v=Cr-RMmXfq58
https://youtu.be/Cr-RMmXfq58

[SomeOtherGuy]

It depends on the specific gun, firing pin, ammunition (primer sensitivity) and height of drop.

I think the AR15 design is drop safe when used with GI type firing pins and ammo with military spec primers. I don't worry about other primer types but in theory it could be an issue, as some are more sensitive than others, and the military spec primers are relatively insensitive. Also, primers that are too high - usually from unskilled home reloading - can be more sensitive.

If you drop a loaded AR15 from 100 feet up (etc.) and it lands on the muzzle I expect it will fire. There are areas of safe and unsafe performance. I figure I have bigger problems to worry about if someone drops a rifle on me from several stories up.

[SteyrAUG]

It depends on the specific gun, firing pin, ammunition (primer sensitivity) and height of drop.



Everything I was just going to type. The real danger of FF firing pins is they are more likely to get stuck in the deployed position by shaved brass or other items that can wedge them in place.

[GH41]

I often wondered how many times you would have to drop the bolt on the same round before it fired if ever.

[SteyrAUG]

I often wondered how many times you would have to drop the bolt on the same round before it fired if ever.

Depends on the gun.

[AndrewWiggin]

Aside from a soft primer, I think it's more likely that you will damage a primer and cause it to be unable to ignite with repeated chambering. I remember reading an article about an LE agency that had several officers who were unable to fire the first round from their magazines on a range day when they expended old ammo.

[TiroFijo]

Why put an opinion vote on a technical question?

[GTF425]

I often wondered how many times you would have to drop the bolt on the same round before it fired if ever.

Never saw it happen on 3 deployments. I used to rotate which round would be chambered before each patrol, but I know a ton of guys who would simply empty and chamber the same round for weeks (sometimes months) on end before shooting it.

I've also wondered if constant rechambering would prevent the round from firing if done like that, but again, I never saw it with those same guys. First round always went bang. For guys who have done the testing, I would honestly love to read the technical data on that for my own knowledge.

[FromMyColdDeadHand]

I often wondered how many times you would have to drop the bolt on the same round before it fired if ever.

I think that owl from the lollipop commercial is looking for work....

So and AR dropped from 100 feet with go off, but the gun is either embedded in the dirt to the castle nut and/or the barrel is bent...

On rechambering, I'd worry more about bullet set back and pressure. Maybe more of an issue with handgun rounds than rifle rounds due to the geometry of the bullet and feed ramps.

Was it Hornady ammo with the re-chambering/firing-pin denting failure to ignite? That was 5-6 years ago? I could just be dis-remembering a dream where my gun won't go off, but that is more a personal problem than a primer problem ;)

[AndrewWiggin]

Why put an opinion vote on a technical question?

Because I think it's interesting to see how people predict outcomes.

[Clint]

Everything I was just going to type. The real danger of FF firing pins is they are more likely to get stuck in the deployed position by shaved brass or other items that can wedge them in place.

True, but the ARFOWs feature positive firing pin retraction, which takes care of that.

[williejc]

My first 1911 bought in 1970 had an instruction sheet(not manual)advising that an inertia firing pin could cause a round to fire if the pistol were dropped from a certain height or higher. I think that this fact was one consideration for the military to require condition 3 carry for 1911s. In any semi auto pistol with an inertia firing pin and no firing pin block, three variables are length of firing pin(was it dressed or trimmed to the "right" length when made), weight of firing pin, and pound rating on the firing pin spring which retracts the pin after hammer strike. Most know that a 1911 firing pin made from titanium and thus lighter would have less risk than a steel one. My 1911 Springfield of 10 years ago came with a titanium firing pin and no block safety. During my youth when rambling wood and stream with a 1911, I kept the chamber empty until I was ready to shoot because I was aware of the risk from dropping loaded 1911.

[Benito]

One of the features of the Armalite AR-10 that I like is the spring loading the firing pin into the retracted position. Probably doesn't make a difference, but heck, why not?

[Moose-Knuckle]

I think that owl from the lollipop commercial is looking for work....

Nice cross thread post, I know I'm old when commercials of my childhood are referenced.




On rechambering, I'd worry more about bullet set back and pressure. Maybe more of an issue with handgun rounds than rifle rounds due to the geometry of the bullet and feed ramps.

Was it Hornady ammo with the re-chambering/firing-pin denting failure to ignite? That was 5-6 years ago?

Yeah seven years ago . . .



This past fall, a large SWAT team here had a failure to fire from an M4 with Hornady TAP ammo during an entry--fortunately no officers were hurt and the suspect immediately threw down his weapon when the carbine went click instead of bang. After the incident was concluded, the team went to the range and expended the rest of their carbine ammo and had one additional failure to fire. This same team had 3 Hornady TAP rounds fail to fire in training a couple of years ago. Last year, when Pat Rogers was teaching a class at a nearby agency, there were 5 failures to fire using Hornady TAP ammo. In all 10 cases, there appeared to be good primer strikes, but no rounds fired. On analysis, the ammunition had powder and checked out otherwise.

http://www.10-8forums.com/ubbthreads/postimages/77993-223primers.JPG

However, two problems were discovered. First, some of the primer strikes had insufficient firing pin indentations. The round from the potential OIS incident had a primer strike of only .013"—the minimum firing pin indent for ignition is .017". In addition, the primers on the other rounds were discovered to have been damaged from repeated chambering. When the same cartridge is repeatedly chambered in the AR15, the floating firing pin lightly taps the primer; with repeated taps, the primer compound gets crushed, resulting in inadequate ignition characteristics--despite what appears to be a normal firing pin impression.

Since then two additional AR15 failure to fire episodes have occurred with other SWAT teams around the country during OIS incidents, with other brands of ammo.

The Army is also aware of this problem and put out the following guidelines in the fall of 2008 to limit re-chambering to 5 or less times (4 times too many in my book...):

http://www.10-8forums.com/ubbthreads/postimages/78110-ArmyPrimerDents.jpg

The current military fetish on constantly loading and unloading creates more problems than simply leaving the weapon "hot".

Re-chambering handgun ammo can also cause problems due to bullet set back and damage to the case rim from repeated extractions.

Bottom Line: Once a round has been chambered, DO NOT RE-CHAMBER IT AGAIN for duty use--relegate it to training only. This is CRITICAL!!!






I could just be dis-remembering a dream where my gun won't go off, but that is more a personal problem than a primer problem ;)

Damn man you have that dream too? I've had it more than once on multiple firearms (GLOCK and AR).

[SteyrAUG]

True, but the ARFOWs feature positive firing pin retraction, which takes care of that.


I have only seen the problem in Galils and some AK pattern rifles. Watched a Galil .308 slam fire and explode because the firing pin got stuck in place.

[nimdabew]

I know for a fact that a 11.5# main spring in a CZ75 with an extended firing pin won't set off a small rifle primer, but a 13# mainspring will.

Take this for what's its worth, but a hammer hiring a firing pin as designed can't set off a small rifle primer if under a certain weight. I think it's a whole lot of worry for little to no risk.

[AndrewWiggin]

Interesting. So my memory wasn't as bad as I feared. I had mis-remembered it as being more rounds than it actually was, but it's still a legitimate concern. A low probability event to be sure, but possible.

In my home defense rifle I insert a round in the chamber by hand with the bolt locked back, then ride the bolt forward and use the forward assist, then insert the mag and close the dust cover.

[GTF425]

Moose Knuckle,

Thanks for that post.