Gun with a 180 bent barrel -- will it explode or will it fire Tom and Jerry way?

[blueskull]

I must admit I was expecting the barrel to explode or at least rupture. I would never dream this to actually work.

[Domagoj T]

https://en.wikipedia.org/wiki/Krummlauf

[Syntax Error]

Okay, so the inventor shoots himself in the head  GENIUS

[Cerebus]

I must admit I was expecting the barrel to explode or at least rupture. I would never dream this to actually work.

Thought of as a machining process, firing a bullet is a swaging operation. That rifle looks to be chambered in 5.56 mm - the mean gas pressure behind the projectile is around 350 MPa, peak is even higher. The yield strength of mild steel is around 210 MPa, the slug in question would be even lower. It's no surprise that a pressure that high can persuade the bullet to deform to squeeze around corners to conform to the barrel.

[chickenHeadKnob]

When I was a young lad, I was something of a gun nut. My parents, who experienced  WWII Germany during their pre-teen years, didn't want any firearms in the house. They were dismayed at my interest and tried to discourage me. They did however relent and allow  me to go hunting with my friends and also join a gun club. At the gun club I received the required safety course which did emphasize keeping mud out of the muzzle and checking for barrel obstruction, because "your barrel could blow up".

At the time I also wondered if barrels would split open like a cartoon depiction. My father said he witnessed FLAK cannons split open because of bad ammunition, perhaps sabotaged ammo as it was made by slave labour. Towards the end of the war boys were enlisted as FLAK helfer (helpers). But those cannon rounds had integral explosive so it still didn't resolve the question for small arms inert lead jacketed bullets hitting a blockage.

At the same time I was in the gun club I would also visit a gun shop/smith and basically be a pest slobbering over rifles I could not legally buy on my own. The owner tolerated me as he probably figured I would be a good future customer. One day I noticed  a rifle in his "to be worked on pile". From the muzzle end to 20 cm back a section of barrel had a big splinter missing and a soft point bullet lodged, with the tip slightly expanded. The gunsmith did confirm it was mud although whatever had caused it was washed away. So I had my answer.

[CatalinaWOW]

All things seem to be possible.  I have seen splayed open barrel ends.  And seen a barrel split almost like a chinese lantern.  Both ends intact but the middle bulged and split.  But have also seen mud plugged barrels fired with little or no ill effect.  But the latter outcome is kind of like winning at Russian Roulette.  Not something normal people would try or count on.

My dad was an amateur gunsmith, and proof fired the products of his work using a heavy load with the gun strapped down and fired remotely in a sand pit.  Hearing chunks of metal whizzing through the air and seeing the aftermath of a failure makes a really strong point of not mistreating these things in any way that you can avoid.

[Cyberdragon]

Mythbusters did a whole segment on this once.

[GlennSprigg]

I had a Lithgow .303 rifle a long time ago when I was 19/20. I 'experimented' with removing more and more
powder from the cartridges, until it would just come out. It seems the slugs are normally quite tight in the
rifled barrel, and one stuck half way. I forgot about it, and ages later I fired a full cartridge into it!!   
Now they were 'really' stuck!! At the time, I thought it miss-fired, but pulling the bolt back released the gas
pressure!!  And nope, the barrel didn't explode...    I pulled it apart, and melted the lead out of the barrel
on the gas stove. It was fine after that!!     (I was young & ignorant then. Not now...)

P.S.   Out of interest to people, many years later, my (educated) older brother was President of the Northern
Territory Gun Club. (Post Army). He demonstrated to me a 'sawn-off' shotgun, using specialized home loaded
cartridges, that was actually 'Tuned' lengthwise, (the pellets somehow 'resonate' down the barrel), so that it
could put all pellets in a 2" diameter circle, at about 40-50 feet!! (No scattering?). Seeing was believing!!   

P.P.S.   He also showed me how most 'movies' were fake, showing 'Silencers' on snub-nosed Pistols. Due to
the fact that the 'powder' is generally still burning after the end of the silencer, so it's still noisy. You need a
long barrel pistol, and fast burning lower power cartridges...  Again, seeing & hearing was believing. 
My Ruger .22 semi had telescopic sights, and a silencer for quiet rabbiting. Nothing 'sinister'. I remember being
amazed how there was NO other sound heard, except the clicks of the trigger!! All history now. Not needed.

[KL27x]

The sawn off shotgun trick? I assume he installed a choke. The choke is what makes the spread tighter; the length of the barrel doesn't matter, unless you allow it to take up a significant percentage of the distance to the target. When you saw the end off a shotgun, you are removing the choke in the muzzle end; that's why the spread increases. The choke is basically a slight reduction in the bore and it has an effect something like a focusing lens.

The silencer can work on any length barrel. It can't work (very well) on a revolver because there's a gap between the cylinder and the forcing cone of the barrel. The gases shooting out of there will be enough to wake the dead. This is also the reason you can't shoot lead reloads in a revolver or a blowback pistol without making a lot of smoke. Lead bullets require lube, and the hot lube shooting out the gap produces the smoke. In a locked breech firearm, the bits that make the smoke can get fully combusted.

There is a revolver called the Nagant (early 1900's or maybe late 1800's?) with a cylinder that moves forward and back. The brass case is longer than the cylinder but crimped over. When fired, the case mouth flares open to seal the cylinder gap. It was military issue in its day. Britian? US? Don't remember. But it was sometimes used with a silencer.

The gases shooting out the cylinder gap can cause damage to the shooter, in extreme cases. You have to be careful how you hold a S&W 500 revolver, or you can end up in the ER with a nasty finger wound.

Your brother sounds like a colorful chap, spreading colorful theories.

[james_s]

Barrels can certainly split open, especially things like shotguns and the previously mentioned flak gun that have large diameter barrels relative to the wall thickness. It's hardly surprising when you think about the fact that a bomb is an explosive substance inside a metal casing and in the case of a propellant like gunpowder much of the force of the explosion is caused by the rupture of the housing.

A bend in a barrel up to about 15 degrees is probably not going to have too much of an effect beyond the obvious reduction in accuracy however you'd have to be really careful to ensure that the inside diameter remains round, it will tend to flatten a bit as the bend angle increases.

[GlennSprigg]

The sawn off shotgun trick? I assume he installed a choke. The choke is what makes the spread tighter; the length of the barrel doesn't matter, unless you allow it to take up a significant percentage of the distance to the target. When you saw the end off a shotgun, you are removing the choke in the muzzle end; that's why the spread increases. The choke is basically a slight reduction in the bore and it has an effect something like a focusing lens.

The silencer can work on any length barrel. It can't work (very well) on a revolver because there's a gap between the cylinder and the forcing cone of the barrel. The gases shooting out of there will be enough to wake the dead. This is also the reason you can't shoot lead reloads in a revolver or a blowback pistol without making a lot of smoke. Lead bullets require lube, and the hot lube shooting out the gap produces the smoke. In a locked breech firearm, the bits that make the smoke can get fully combusted.

There is a revolver called the Nagant (early 1900's or maybe late 1800's?) with a cylinder that moves forward and back. The brass case is longer than the cylinder but crimped over. When fired, the case mouth flares open to seal the cylinder gap. It was military issue in its day. Britian? US? Don't remember. But it was sometimes used with a silencer.

The gases shooting out the cylinder gap can cause damage to the shooter, in extreme cases. You have to be careful how you hold a S&W 500 revolver, or you can end up in the ER with a nasty finger wound.

Your brother sounds like a colorful chap, spreading colorful theories.

Thanks for your info. That's interesting, thank you.  However, regarding your last line, it wasn't 'theory'!! 
As I first explained, that "Seeing, (and hearing), was believing", as he demonstrated it all on the Range.
It was maybe 20-25 years ago, so I forget if he mentioned a 'choke' in the shotgun barrel. Maybe so? However,
he had about 3 or 4 'sawn-offs', (amongst many other rifles/pistols). He explained, (and demonstrated), how the
pellets can move in a 'wave' pattern down the barrel, and by 'tuning' the length precisely, just when the pellets
were at the point of converging again, (or the 'pressure' wave surrounding the pellets?), they would stay together. 
Evidently this also required precise home-assembled cartridges, for consistency. 

[Ed.Kloonk]

The Lithgow factory now is a museum.