[RANash]

On the TV show, they claimed that a .22 revolver can do a "sympathetic discharge" where the recoil due to firing the intended cartridge causes a cartridge in one of the other cylinders to fire. The second cartridge isn't fired out through the barrel, but just comes out the cylinder.

Is there any truth to this?

On the show, they said it was rare, and could only happen with a very poorly made revolver.

Doesn't seem right to me. If the cylinder was extremely loose, then recoil could make it slap backward, but still, what would strike the rim of the second cartridge to make it ignite?

Any truth or just more Hollyweird bs?

[Jim March]

Huh.

{scratches head}

It's a new one on me, BUT, if a big enough piece of grit was sitting on the blast shield face and formed a "firing pin" that way...:scrutiny:...I guess it's not totally impossible.

The accuracy on that second round would REALLY suck. Ditto velocity.

[RUT]

Yeah, I saw that segment last night and wondered the same thing. Could you believe the amount of slop in the cylinder?? That thing made a "Saturday Night Special" look good!!:(

[RANash]

The accuracy and velocity would really be bad. In fact, that came into play in the story.

Grit on the blast shield face...that makes the best sense...maybe.

Imaginative script writers!

[RANash]

I guess I should have done some research first. Here's two items I found on the 'Net.

The first is from a firearms recall notice:

--------------------------------------
C.O.P.
MODEL “COP”,
357 MAGNUM CALIBER, 4 BARRELED PISTOL

WARNING: This make and model pistol may have the potential for “SYMPATHETIC”, MULTIPLE CHAMBER, DISCHARGE and may DISCHARGE WHEN DROPPED.

The C.O.P. pistol design did not incorporate a Drop Safety until late 1982 or early 1983. Pistols produced before this time-frame may be subject to discharge if dropped. At approximately the same time an internal design change was incorporated to prevent the retaining plate from allowing a second firing pin from coming in contact with a live cartridge not under the hammer.

Bellmore Johnson Tool Company
445 Putnam Avenue
Hamden, CT

Source:

AFTE Journal, January 1982; Volume 14, Number 1:44-47

AFTE Journal, October 1983; Volume 15, Number 4:18
-------------------------------------------

The second is from a RCMP (Royal Canadian Mounted Police) firearms terminology page:

--------------------------------------------
Sympathetic discharge
The simultaneous firing of two or more cartridges chambered in the cylinder of a revolver, only one of which is in an exact alignment with the barrel; normally associated with percussion revolvers.
--------------------------------------------

Live and learn.

[Jim K]

Yes, it can happen with a .22 or any rimfire cartridge.

What happens is that on revolvers, the recoil of the cylinder can drive it back hard enough that if there is too little headspace, the rim of a round that is not in line with the barrel can be pinched between the cylinder and the recoil shield and the round can be fired. There doesn't need to be dirt or grit on the shield, just enough setback or an especially sensitive priming compound. That is what was meant by a cheaply made revolver; better quality guns have adequate headspace and often countersunk case heads.

That round being out of line with the barrel, the bullet will usually strike the frame or something else and either stop or be deflected.

Jim

[Archie]

If the cylinder is loose enough to allow subsequent rounds to impact the recoil shield and fire, how is it the firing pin can make firm enough contact with the round that is supposed to fire?

Sounds like one of those "every thing going wrong at once" scenarios.

[BluesBear]

Now I wouldn't say that a sympathetic discharge, which was called a "chain fire" in a percussion revolver, would be impossible in a rimfire revolver but what I will say is that it would be nearly impossible to purposly make it happen without seriously altering the gun.

To say that the recoil of one cartridge firing could setback the cylinder with enough force to fire a second cartridge is an oversimplification. You have several other forces at work here besides recoil. For one you have the force of the hammer/firing pin pushing the cylinder forward. It takes a pretty severe localized blow to discharge a rimfire round.

I did a test in High School regarding the force needed. Hey this was the late 60s/early 70s. We were using the cylinder from a Rohm revolver, turned around so the EMPTY primed .22LR cases could be inserted from the front. The whole thing was chucked in a vise and hit with various hammers.
It took a pretty good smack with a small ball peen hammer to do it. We broke the handle of the tack hammer we started with with no succesful firings. I fact we destroyed more than a few with no ingition.

So while I won't say it could never happen.....

but I doubt you could find a high school to let you try. :D

[Pendragon]

Well, my .22 Ruger had so little recoil, I dont hardly see how it could happen.

The .22LR just does not have enough oomph IMHO to do it.

I have heard that in the black powder days, you could get sympathetic discharges - supposedly, this is why there were very few revolver-rifles - if they symp-fire, you lose digits :what:

[jem375]

Black powder pistols in the old days used to double fire like that......that's why they had to put grease over the cylinder face to keep it from igniting the powder in the other cylinders........find it hard to believe that a modern day revolver would do that though.............

[Mike Irwin]

Recoil causing sympathetic discharge...


BBBBBBBBBBBBBBBBBWWWWWWWWWWWWWWWWHAHAHAHAHAHAHAHAHA!

Holy :cuss:ing :cuss:, what DUMB A$$es!

In fact, they get the latest Mike Irwin "Hey, you're a dumb a$$, you know that?" award!

WHAT recoil from a .22 revolver?

God give me strength...


Well, chuckles aside, I guess ANYTHING is possible...

I guess it's even possible that one day CSI will be worth watching, instead of just more canned chicken:cuss: pablum that panders to the stupidest common denominator -- the average TV viewer... :rolleyes:


RAN,

That is a completely different situation involving the COP derringer.

[RANash]

What! CSI isn't factual? Say it ain't so!

I think the one that really cracked me up was where they trapped air from the crime scene (12 to 24 hours after the crime, and an outdoor crime scene) in a plastic jug and then had a blood hound sniff the air and track down the perp. This was on the Las Vegas version of the show, where, I guess, they never get any breeze!

Thanks all. I remarked to my wife while we were watching and wondering if there was any validity to it, "I'll ask the guys and gals on THR. Then we'll find out if it's possible."

Gotta admit, they're creative scriptwriters.

[Old Fuff]

A friend of mine blew-up an old .45 Colt Single Action Army revolver while I was standing next to him. Both the top strap and upper half of the cylinder ended up somewhere in outer space.

We think that one of his handloads had a high primer, and when he shot the cartridge aligned with the barrel there was enough end-shake in the cylinder to allow the next round to hit the recoil shield hard enough to set the primer off. This sort of thing isn't common, but it does happen. I rather doubt it would happen in most .22's because the casehead (rim) is usually in the chamber which is counterbored to support it.

[BluesBear]

Both the top strap and upper half of the cylinder ended up somewhere in outer space.
I seriously doubt that that was caused by a chainfire.

More than likely a double powder charge was to blame.

The primer would have had to hit the bottom of the primer pocket before it could have fired. The recoil shield would have just seated the primer flush so the anvil legs wouldn't be touching the bottom of the pocket.


I once saw a Walker Colt replica fire all SIX chambers (on the very first firing) more or less at once by a maroon who didn't believe greasing the chambers was actually needed.
:what:

Maroon ended up with a sprained wrist. Gun was VERY dirty with lead smears everywhere!
I was standing to his right and was hit by a flying percussion cap as the other five were all blown completely off the nipples.
But other than cosmetics there was no damage to the revolver except for the slight peening of the loading ram. And this was done with the max reccomended loads.


That was over 20 years ago I had forgotten how funny that was.



:D

[Daniel Watters]

I suspect that a sympathetic discharge in a rimfire revolver would require not only a problem with endshake, but poor chamber/barrel alignment due to sloppy timing.

[Old Fuff]

BluesBear:

No it wasn't an overstuffed handload. Two cartridges went off at once.

Chain fires happen in caplock revolvers when the flash from one shot somehow ignites the powder in a second or more chambers. I have never seen, nor heard of a true chain fire in a cartridge revolver.

[BluesBear]

Old Fluff,
Which other cartridge went off? If only two cartridges fired simultaniously "the top strap and upper half of the cylinder" would not have "ended up somewhere in outer space".

I seriously doubt that two adjacent ignitions at once would do such damage. Now if you had said that TWO chambers were blown open that might have some creedence. But the damage you describe is totally consistant with an overcharged cartridge condition.

For those who have never seen such an occurance. The over pressure cartridge peels the top half of the cylinder off and either bulges or removes the topstrap. The cartridges or cases on either side are usually destroyed in the process. The open flame of the overcharge often ignites the powder in the adjacent cartridge(s). In your case how many cartridges were destroyed? Where did the bullets go?

To truely have a sympathetic discharge due to a high primer, (I used the term chainfire previously only to describe the effect of more than one chamber firing) you would have to have a cartridge with a shallower than standard, or somehow otherwise blocked, primer pocket. Remember in several of the old time loading tools you actually tapped the die with a hammer to seat the primer.

And isn't is questionable that whenever you hear of a so-called sympathetic discharge that it's ALWAYS the chamber immediately next to the firing chamber?

I still doubt that a sympathetic discharge is possible in an otherwise normal firearm. Especially since the case you describe was using handloaded ammunition, I still vote double charge.


Just my learned tuppence.

[clem]

On CSI Miami, anything is possiable!

I'm sorry to hear that you don't have a life so you must watch that foolish program.

[Old Fuff]

BluesBear:

In this particular incident the second cartridge that went off was on the right hand side next to the ejector tube/assembly. We fould lead smears on the frame and tube, but have no idea where the bullet went. The remains of the case head were still in what was left of the chamber, and we later removed the primer and examined it. There was no indentation of any kind, but it was flattened and obviously had gone off.

During the last 50 years or so I have examined a number of "blown" revolvers. Besides the obvious reason (an overcharged reload) several were designed for black powder, and never intended for the smokeless charge that was fired in them. In any case I think that this old Single Action's cylinder failed in the way it did because of thin chamber walls. Had it been bored for a smaller cartridge the results might have been slightly different. I can assure you that when this happens to someone standing next too you it gets your attention quick!

I have heard reports of similar incidents happening where factory ammunition was being used, but I've had no personal experience with them. If they really happened in the way described I'd strongly suspect excessive headspace combined with excessive cylinder end-shake. Some people shoot stuff that would scare me out of 10 years of lifespan .....

[BluesBear]

Old Fluff,

The lead smears on the ejector & tube are the givaway here.

If the cartridge had fired before the cylinder was compromised there would have been a lot more damage to the ejector assembly. After the cylinder gave way the explosion of the fired cartridge ruptured the secondary cartridge and cause it to "fire" as well. The flattened primer is a natural occurance.


In testing we did back in the 1970s on the force needed to fire a primer we were using empty cartridges held in a vise, using a weighted swing arm to achieve ignition. In every case where the primer fired there was also excessive primer setback due to there being no recoiling of the case to keep it seated.



If you have ever used the CCI plastic practice bullets in .45 there is a notice in the instructions to use cases with an enlarged flash hole to prevent primer setback. If you don't and fire them in a revolver the cylinder will lock up and not rotate.

Nick, a friend of mine back in Kentucky, was practicing in his basement with the CCI plastics in his 45 Colt New Service. After locking it up tight he reread the instructions. He then enlarged his flashhole. The rub was he enlrged them to almost full primer diameter. Somewhere between 1/2 and 2/3 would fire. With the rest the primers were pushed too far into the case to fire and some were harmlessly pushed completely into the case.


Also remember that heavy recoiling handguns had a tendency to have the bullets move forward from recoil which is why heavy crimps are needed in heavy loadings. So that would imply that recoil forces actually pull the cartridges away from the recoil shield at the monent of firing.

[RANash]

I'm sorry to hear that you don't have a life so you must watch that foolish program. Ooh...good shot! I actually have been thinking that I really need to cut down on TV...