Blown Barrel - Wow!

[reconbob]

I have been meaning to post this and recent discussions made me think this

would be of interest.

 

The barrel is from an old West Hurley Semi Auto Thompson. The owner had

shot many thousands of rounds over many years and then one day BOOM.

 

This barrel is of great interest to me because I have seen my share of blown barrels

and when I look and the big bulge at the rear, then IN FRONT of the bulge the blown

out barrel and at the very front the barrel the front sight mounting ring is badly bent.

 

All of this with .45 ACP. I think whatever happened here is not the simple stuck

bullet struck by next bullet because of the so much damage in front of where you

would figure the stock bullet to be.

 

Maybe first bullet stuck at the muzzle, then second bullet stuck at the rear,

then the third bullet pushes the second bullet ahead to the first one and now

the barrel blows open?

 

What do you think?

 

Bob

[Paladin601]

Reloading is dangerous.

[DougStump]

Reloading is dangerous.

Only reloads that are done by a careless person. In almost 50 years of reloading the worst problem I've had is a couple of bad primers out of I wish I know how many thousands of rounds. OTOH, I've personally had two factory rounds with no powder ( and witnessed a third) and one with no flash hole.

[Big Al]

I tend to agree with you, Bob, that it's a case of multiple squib loads.

 

Bullet from squib one lodges near the muzzle. Bullet from squib two lodges further back, creating an air space between the two lodged bullets. The follow-on full strength round(s) (however many it took) then compress the rear lodged bullet forward, compressing the air in between, eventually leading to the rupture.

[reconbob]

The guy used factory ammo.

 

 

Bob

[StooperZero]

The guy used factory ammo.

 

 

Bob

 

 

I've had more "occurrences" with factory ammo than any of my handloads in the past 10 years. My list of what I will actually buy off the shelf is pretty short.

[Orion]

Bob,

what are the chances of a defective barrel metallurgy causing such damage to this barrel?

[full auto 45]

I would agree about the multiple squibs. But the bend at the front site IS impressive.

[Petroleum 1]

Cheap metal? over heated barrel?

[ppgcowboy]

What would stick a bullet at the front of the barrel? I am wondering if this is either planned or a perfect comedy of errors. Perhaps the front had a previous plug in it. Then a perhaps a primed but no powder bullet was shot that pushed a bullet into the lands and grooves. This bullet is not enough to cycle the action so the shooter had to cycle it, loading a good live round and then the excitement begins.

Did the owner have an explanation?

Edited January 26, 2018 by ppgcowboy

[reconbob]

The guy was the original owner of the gun purchased back in

the late 70's or early 80's. He has shot is over all those years with

no problem.

I don't think we'll ever know the exact cause.

I do not think the steel of the barrel is to blame here. It's interesting

that what ever DID happen created pressure many times greater than

you'd expect with .45 ACP.

[DougStump]

Squib, yes. But I would also suspect a flaw in the steel. I don't have any data on pressures involved, but I'll bet the bolt would blow back before the barrel would go ka-boom. I witnesses a full auto UZI suffer a squib. The first bullet lodged very near the muzzle. The next bullet stopped right behind the first. Repeat until the barrel was full of cast lead bullets. In a fraction of a second rounds wouldn't chamber. The barrel was somewhat bulged, but not ruptured. It was also FUN getting the barrel out!

[MG08]

You would need to look at the barrel and actually look at grain structure and crack propagation. Photos are not clear enough or close enough to evaluate, It is quite possible that the failure traveled through the steel - from one stuck bullet- but I have seen a LOT of squibs stuck in barrels, next round fired, and in low pressure pistol ammo, a failure like this is unusual. You usually see them blow out the back in an open bolt SMG, and act like an out of battery failure. The key may be that it is a semi auto firing from a locked breech maybe ?

[Paladin601]

I have never had a squib load on Factory ammo, and never a squib on reloads, I inspect and weigh each round. W#as taught that a long time ago. Never have found one either. I don't use the cheapest ammo either.

[Paladin601]

The guy was the original owner of the gun purchased back in

the late 70's or early 80's. He has shot is over all those years with

no problem.

I don't think we'll ever know the exact cause.

I do not think the steel of the barrel is to blame here. It's interesting

that what ever DID happen created pressure many times greater than

you'd expect with .45 ACP.

Good chapter in Hatcher's notebook on that, about double and triple loads of Bullseye

[buzz]

 

I tend to believe that the second bullet hitting the back of the first bullet is what causes the bulge, not an air pocket being compressed.

 

Look at the way the lead squirted out of the barrel in this video.

 

Lead is a weird metal, it has the property of flowing like liquid when under very high stress.

 

I also don't think that a ruptured barrel is a big deal.

 

the PRESSURE of combustion is an accelerant for the combustion rate. so anything that prevents the bullet from uncorking the barrel can drive the pressure way higher than normal.

 

so when a bullet gets stuck or a cartridge is fired out of battery, the effect varies from no harm at all to the gun, to the gun blowing apart.

 

It all depends on how much pressure builds before it's vented and how it's vented.

[buzz]

I have never had a squib load on Factory ammo, and never a squib on reloads, I inspect and weigh each round. W#as taught that a long time ago. Never have found one either. I don't use the cheapest ammo either.

 

you weigh each round?

 

RCBS makes a nice powder checker die

 

also, you can tape a light to your press and peek into each case before you seat the bullet. a visual inspection is as good as weighing the round

[Paladin601]

 

I have never had a squib load on Factory ammo, and never a squib on reloads, I inspect and weigh each round. W#as taught that a long time ago. Never have found one either. I don't use the cheapest ammo either.

 

you weigh each round?

 

 

Yeah, I do, weird huh. And if they have an extreme difference, I don't use them

[Got Uzi]

I love that video as he is standing there with a Thompson that has an obvious bore obstruction and has no chance in Hell of shooting again in its current state, and yet he doesn't pull the mag out LOL

[reconbob]

It would be interesting to know what's the air pressure created

in a barrel when the next bullet is fired and pushed against the stuck

bullet? Because when this happens you don't have the safety "valve"

of the bolt being open at the rear allowing as to escape.

Most of the blown barrels I have seen ruptured align the corner

of the grooves of the rifling.

I forgot to mention on the gun that this happen on the bolt recoiled

back with such force that the firing pin support pin - a small pin (maybe 1/16"

was sheared off when the bolt hit the back of the receiver and the

firing pin then moved to the back as well.

 

Bob

[Taliaferro]

Was the factory ammo Wolf? Kahr has already warned of problems with barrels when using the Russian ammo.

[Paladin601]

Was the factory ammo Wolf? Kahr has already warned of problems with barrels when using the Russian ammo.

I think you hit the nail on the head

[67ray]

It would be interesting to know what's the air pressure created

in a barrel when the next bullet is fired and pushed against the stuck

bullet? Because when this happens you don't have the safety "valve"

of the bolt being open at the rear allowing as to escape.

Most of the blown barrels I have seen ruptured align the corner

of the grooves of the rifling.

I forgot to mention on the gun that this happen on the bolt recoiled

back with such force that the firing pin support pin - a small pin (maybe 1/16"

was sheared off when the bolt hit the back of the receiver and the

firing pin then moved to the back as well.

 

Bob

 

 

This is easy to model. Air around atmospheric temperature and pressures is modeled with the Ideal Gas law. Didn't do the arithmetic but my gut tells me it is unlikely the pressure would be high enough to rupture a barrel.

 

The barrel would be modeled as a thin walled pressure vessel (TWPV).

[GUNGUY45]

It would be interesting to know what's the air pressure created

in a barrel when the next bullet is fired and pushed against the stuck

bullet? Because when this happens you don't have the safety "valve"

of the bolt being open at the rear allowing as to escape.

Most of the blown barrels I have seen ruptured align the corner

of the grooves of the rifling.

I forgot to mention on the gun that this happen on the bolt recoiled

back with such force that the firing pin support pin - a small pin (maybe 1/16"

was sheared off when the bolt hit the back of the receiver and the

firing pin then moved to the back as well.

 

Bob

I had a W. Hurley Semi, late '80's vintage that would regularly break the firing pin support pins.

It did it with factory ammo, & reloads.

After a few times I replaced the W. Hurley pins with titanium pins that I made.

the breakage stopped, & I never saw any other problems from the gun.

I had over 10,000 rounds through it after the pin replacement, when I sold it.

I think they had the pins too brittle.

[Junkhunter]

I have seen rifles loaded accidentally with fast burning rifle powder detonate in the chamber and blow the gun. I have seen a revolver with such a light sprinkling of powder in the case detonate as well. No pressure curve just one spike because the powders burn rate never happened. Again these blow up the whole gun. I once saw a guy shooting away no powder just primers and filled up a whole barrel of a 4 inch 38 before the last round backed up between the forcing cone and cylinder jAmming it. I'm betting a squib backed up by a live round. If the Thompson had a lot of rounds thru it the primer alone may hAve pushed the bullet close to the muzzle.although I doubt primers would operate the bolt. Edited January 27, 2018 by Junkhunter