Question about squib


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moewadle
March 23, 2012, 08:37 PM
I was at the range today shooting a SW Model 25-11 45 Colt. It has a 6.5 inch barrel I believe. I was shooting ammo reloaded by someone else and had a squib. Apparently no powder at all...because the primer blew the slug about 1/2 inch into the barrel. My question...what if I had not realized what had happened and pumped another live round into that slug. This firearm was made in 2001 and had not been shot that I know of until I bought it a month ago. What is the worst you have heard happening when shooting behind a slug caught in the barrel of a high caliber revolver?

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rcmodel
March 23, 2012, 08:41 PM
Generally a second shot behind a stuck bullet will ring or bulge the barrel, ruining it.

But a more dangerous consideration is:
If the careless handloader didn't get powder in one load?
How do you know for sure the next one he loaded doesn't have a double-charge in it that will blow up the gun??
Well, you don't know!

I'd put those handloads where the sun don't shine, and never shoot another one of this guys handloads!!

rc

oldfool
March 23, 2012, 08:45 PM
roll your own (and pay close attention), or buy off-the-shelf
you can only have just so much fun (on the cheap)
friends don't let friends shoot ammo unknown, ammo loading friend known or not
bad way to ruin a good friendship

BCRider
March 24, 2012, 01:44 AM
Yep, what RC said. But I'd deal with them differently. If you're shooting a gun which takes .45Colt rounds you are crazy or very rich with lots of disposable income if you do not get into reloading your own ammo for this gun.

With this in mind one of the first tools you should get is an inertia bullet puller. Pop those reloads and see how much powder is in the end of the clear plastic "hammer head" for each. If you don't find a double charge or another squib at least you'll have some pre-primed cases and bullets to use for your own more carefully inspected loads.

It's good that you caught the squib before you pulled the trigger again. Even with with the relatively soft cowboy loads the second bullet slamming into the stuck squib bullet will generate many thousands of lbs of force outwards which try to bulge the barrel as the two bullets crash into each other. Lead is highly malliable of course. We know this. So when two bulelts collide in a barrel they don't just kick at each other like pool table balls. They distort and swage each other and act very much in a hydraulic like manner. And the inertia of the stuck bullet means that the one behind has no where to go other than sideways.

skidder
March 24, 2012, 02:22 AM
For me hand loading has always been safer (never had a problem), but I have had two factory brands, federal and Remington, get stuck in my barrel. I would never shoot reloads from other people, unless I was there and watched them do it.

sirsloop
March 24, 2012, 02:30 AM
Simple... Choose powders that will overfill on a double charge, and get in the habit of visually checking both the powder in the case and watching a powder cop. H110 in .357magnum is ok, but you could seriously overfill a 500 magnum. Rifle rounds typically are filled nearly up (or in some cases compressed!!) so they are not too much of a concern.

I've never had a problem with my reloads other than a few stubborn primers... I've run into some plain puss poor factory stuff. At least my hand loads have personal attention given to each step in the process.

jhco50
March 24, 2012, 02:54 AM
:) I can answer this question. In a Ruger Vaquero (old model) .45 LC, it will shoot the other bullet out of the barrel, but bulge the barrel. Then, if you can find a replacement it will cost you to replace said barrel. You were more observant than me you lucky dog. LOL

Jim K
March 25, 2012, 10:01 PM
A lot depends on where the obstruction (stuck bullet in this case) is. If it is immediately in front of the second bullet, with the bullets touching (not likely in a revolver), the two bullets will simply be fired as one. In an experiment, I filled the barrel of an M1911 clone (Norinco) with lead bullets leaving just enough room for a live GI round to chamber. On firing, all bullets left the barrel and were recovered from the sand trap. The recoil was excessive but there was no damage to the gun.

But if the rear bullet moves enough to pick up a significant amount of kinetic energy, and then encounters an obstruction, the energy will be converted to heat, the barrel will be softened by the heat and the pressure will bulge or burst it.

So there is no easy answer, and a lot depends on the bullet velocity at the time of impact (and hence the kinetic energy), the thickness of the barrel and its ability to absorb heat, the type of obstruction and whether it can move or not, etc.

Jim

1911Tuner
March 26, 2012, 07:14 AM
But if the rear bullet moves enough to pick up a significant amount of kinetic energy, and then encounters an obstruction, the energy will be converted to heat, the barrel will be softened by the heat and the pressure will bulge or burst it.

I'm glad that somebody with some understanding and experience brought this up. I've become something of a pariah for even suggesting it.

Rapid, extreme air compression also generates a lot of heat in quick time. In a Diesel engine, it creates enough to light the fuel/air mixture in the cylinder...and diesel fuel isn't all that volatile.

moewadle
March 26, 2012, 11:43 PM
who reloaded the ammo in which I had the squib. I told him that the concern had been stated to me, "If he missed a charge of powder in one shell maybe he got a double in another." He said that would not happen because the shell case has insufficient room for a double charge of powder.

Jim K
March 26, 2012, 11:48 PM
Well, I have taken a lot of "heat" for saying the the problem comes from heat. Most folks insist that either 1) the bullets expand sideways and burst the barrel or that 2) the compressed air does so. But experiments have been run with hardened steel bullets (which were measured before and after and didn't expand) and with obstructions that have had the middle drilled out so any air betwen the bullets could escape. The results were the same. When that energy dump takes place, the amount of heat is more than enough to cause barrel steel to act like a soft chocolate bar and stretch. And if it stretches enough it bursts.

The heat lasts too short a time to discolor the barrel steel or even harm the bluing, so even someone examining the barrel afterward won't immediately associate the problem with heat.

Also, and this is just MHO, I think that many of the Ka-booms in auto pistols are really due to barrel obstructions. And here is how I think it happens:

A shooter with two calibers of ammo, .45 and .40 or .40 and 9mm, gets the wrong round in a magazine, probably the top round. Most magazines will accept the smaller round and hold it.

The shooter inserts the magazine in the pistol and racks the slide. The small cartridge is put into the chamber but misses the extractor and momentum pushes it in far enough that it is not seen. The shooter thinks the top round failed to feed and racks the slide again. If he points the pistol down, the small round will fall out, but chances are he is trained to keep the pistol "pointing down range". So the second, proper size, round goes up the tube and is fired. Its bullet strikes the live round in the barrel; its inertia causes it to act as a obstruction, plus its primer goes off and blows the bullet and case out the barrel. Can I prove that any Ka-boom was actually caused that way? No I can't. But several statements I have seen lend some support to the idea.

Jim

BaltimoreBoy
March 28, 2012, 11:48 PM
Jim_K, or 1911Tuner:

Have either of you some links or data of your own on the culprit being heat? I don't think I have seen this view presented before. On first hearing it, my impulse was to reject it - but reflection seems to make it more plausible.

1911Tuner
March 29, 2012, 06:42 AM
I can't speak for Jim, but my theory was born from my own observations. I did see evidence of intense heat in a bulged barrel once after I actually cross-sectioned it for closer examination. As Jim mentioned, if the driving bullet is touching the lodged bullet when the trigger is pulled...they both leave the barrel without bulging or bursting it. The bulge happens when there's a gap between them.

BCRider
March 29, 2012, 04:08 PM
Jim and 1911, I do not at all doubt that a lot of heat would be involved. As you both indicated a lot of work energy from the second round is being converted from motion to something else. And the lowest common denominator in any such conversion of energy is eventually heat. There's the, probably minor, heat from the air compression and there's the heat from deforming of the two bullets. After all if you work metal the metal heats up internally. It's just that normally there's a big anvil face or other hard metal surfaces to sink it away. But I'll bet that if one could mash a bullet on a ceramic surface with a hammer which is also a poor heat conductor that by the time it was "coin like" you would find that you could barely hold it from the metal being hot.

So yeah, when so much energy is released in such a short time it's only logical and should be expected that the bullets and barrel will be heated up a lot on the internal portions. However steel is a generally poor heat conductor as metals go. So the heat will not show up on the outside immediately. And when it does it'll be dispersed through more of the wall of the barrel. So it may not seem like it's all that warm to an outside checking the outside of the barrel. But you can bet the inner surface and rifling got FAR more energy in it as heat.

Jim K
March 29, 2012, 10:56 PM
The culprit is heat. I asked a metallurgist to look at a section of a bulged barrel under a microscope and his reaction was on the order of "wow, this got real hot!" If the barrel is thin, it bulges or bursts. If it is thick (like a heavy "bull"* barrel, the heat may be absorbed before it softens the outer part and visible expansion may be confined to the inside.

When the barrel bursts toward the muzzle, the pressure behind the second bullet has a major effect, since it is that pressure that causes the barrel to "flower" and peel back.

But the real cause of a burst barrel from an obstruction is the heat generated when a bullet stops on the obstruction.

Another interesting point. Note I said "bullet stops". What if there is no bullet? What happens if I get a bullet stuck in the barrel (or some other obstruction, like a bore snake) and decide to load a case with a half charge of powder with no bullet and shoot the obstruction out? (I can hear the shreiks of "You will blow up the gun" now.) Nope. The gas from the powder does not have enough compact mass and pick up enough kinetic energy to create a heat dump; the obstruction will be blown out and the barrel will be OK.

NOW DO NOT DECIDE TO GO SHOOTING OUT OBSTRUCTIONS WITH LIVE AMMO WITH BULLETS AND THEN BLAME ME WHEN THE BARREL BURSTS. I SAID A HALF CHARGE AND NO BULLET, DAMMIT, NO BULLET!!!!!

*The name comes from Freeman Bull, a Springfield Armory worker who advocated the use of heavy barrels for military match rifles.

Jim

jungle
March 30, 2012, 03:37 PM
Heat is one theory, perhaps a better one is that a bullet moving with enough energy has the ability to obturate the bullet left in the barrel or moving down the barrel thereby forcing the barrel to bulge.

The momentary heat from compression would not soften the steel any more than the 1500 degree heat of an internal combustion engine softens cylinders. Too much adjacent metal serves as a heat sink.

In any case, an obstruction will ruin your barrel and maybe your day, whether it be snow, mud, a bullet or even a cleaning patch.

1911Tuner
March 30, 2012, 04:58 PM
Earlier posts by Jim K:

A lot depends on where the obstruction (stuck bullet in this case) is. If it is immediately in front of the second bullet, with the bullets touching (not likely in a revolver), the two bullets will simply be fired as one. In an experiment, I filled the barrel of an M1911 clone (Norinco) with lead bullets leaving just enough room for a live GI round to chamber. On firing, all bullets left the barrel and were recovered from the sand trap. The recoil was excessive but there was no damage to the gun.

And:

I asked a metallurgist to look at a section of a bulged barrel under a microscope and his reaction was on the order of "wow, this got real hot!"

I think that rapid obturation is also involved, but without heat, obturation alone couldn't do what I've seen done.

BCRider
March 30, 2012, 05:45 PM
If a guy that knows metals said there was a lot of heat then that's more than good enough for me.

You guys are still thinking in terms of propane or welding torches as a heat source. But a sudden short term flash that generates a whopping big spike of temperature rise can easily reach 10 to 20 thou into the metal of the barrel before it begins to dissapate through the rest of the barrel's mass. Just as noted where a diesel engine uses compression to heat the air to well above the flash point of the fuel. But when you think that this is happening with lead and far, far higher pressures in the impact zone the idea of instantly very hot temperatures which you would not later feel on the outside of the barrel becomes very likely.

You have to remember too. He mentioned the heat in the last post but both heat and pressure before that. You need to read the whole thread. It's the pressure of the two bullets hitting each other that generates the heat which both damages the barrel to some extent on its own and at the same time weakens the rest of the metal and allows it to bulge from the pressure.

Driftwood Johnson
March 30, 2012, 09:18 PM
Howdy

I dunno why you guys keep talking about burst barrels. I have seen far more burst cylinders in revolvers than burst barrels. The thickness of the steel of a barrel is much more than the thin spots in a cylinder, particularly a large bore revolver. In my experience, if a bullet lodges in the barrel, particularly in the forcing cone, and another bullet is fired, the cylinder is far more likely to burst than the barrel.

Has nothing to do with heat, it is a pressure problem.

Yeah, I know, some folks think that the pressure will dissipate out of the barrel/cylinder gap before it builds high enough to burst the cylinder. I don't think that is necessarily true, I think with a bullet lodged in the barrel pressure can build faster than it can escape out of the gap.

jungle
March 30, 2012, 10:29 PM
That is true, a burst cylinder is often caused by a double charge or a second bullet near the breech of the barrel.

Back to the heat theory, anyone care to post the temperature rise for the compression of the volume of air in a barrel with a lodged bullet? Here is a hint, it isn't as large as some of you think it is.:D

Most of that energy will be expelled in bullet obturation, and with or without heat, that is enough to do the job.

1911Tuner
March 31, 2012, 06:29 AM
Most of that energy will be expelled in bullet obturation, and with or without heat, that is enough to do the job.

Then why did Jim's barrel stuffed with bullets not cause a problem? Lead is malleable enough to obturate with or without a running start. Seems to me that when the theory doesn't jive with the results of the experiment, we should probably believe the results, no?

Heat is involved in this...both from the impact and from the violently compressing air plug. I've seen evidence of it even without a microscope. Obturation is also involved.

The Old Redneck
March 31, 2012, 07:48 AM
Question was off topic.

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