Never tried this with a gun, and don’t intend to, but suppose one took a gun (maybe a pistol) and pressed it up directly against a steel door so that the barrel opening is directly on the steel itself; no place for air to escape, and opens fire. Is it likelier that the bullet would pass through the steel door, or that the lack of escape vent for the gasses would make the gun blow up?
If you’re a human pressing the gun up against the door, you’re not going to be able to seal it sufficiently to prevent the gasses escaping - the gun will not explode. Whether the bullet will pass through the steel door or bounce off depends on the both the bullet and the thickness of the door.
I think you’d need to weld the barrel to the door to have it sealed well enough that the barrel would explode. If it is mechanically sealed well enough that the gas cannot escape quickly or force a separation of the door or barrel then the type of pistol will make a big difference. A revolver will blow a lot of gas back out through the area of the cylinder. I doubt the bullet develops much velocity with similar pressures in front and back of the projectile. It may be possible that enough gas escaping the rear of the barrel causes the bullet to change direction and slam back into the cylinder. I don’t know what would happen in an automatic but I can see destruction of the loading mechanism being likely.
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I think you’d need to weld the barrel to the door to have it sealed well enough that the barrel would explode. If it is mechanically sealed well enough that the gas cannot escape quickly or force a separation of the door and barrel then the type of pistol will make a big difference. A revolver will blow a lot of gas back out through the area of the cylinder. I doubt the bullet develops much velocity with similar pressures in front and back of the projectile. It may be possible that enough gas escaping the rear of the barrel causes the bullet to change direction and slam back into the cylinder. I don’t know what would happen in an automatic but I can see destruction of the loading mechanism being likely. In any event, the pressure at the front of the barrel should build up very high as the bullet approaches the door and will slow it down a lot.
I’d assume gun manufactures do a number of tests to determine the strength of the barrel and other mechanisms that would allow a pretty close prediction of this circumstance. A steel door typically has lightweight core with steel skins on either side which is probably around 16 gauge. A ramset load will easily penetrate that so the door itself isn’t much of a factor.
I’m going to guess too that if the barrel is sealed (but as noted above, pressing it to the door won’t sufficiently seal it - welding required) then the pressure is on the shell casing. Depends on the pistol, will it com flying out the back, or push back and jam against the hammer and the exposed part of the brass cartridge shatters onto anyone holding the gun, or the back end of the cartridge breaks, etc.?
I seriously doubt you can blow up the barrel - most of those a re pretty solid steel compared to the other “weakest links”. Keep in mind this is an explosion - unlike in Hollywood, where numerous people have outraced giant shock waves, an explosion happens in fractions of a second and anything too weak, the weakest part will fail first. In my totally unprofessional opinion, that’s going to be one end or the other of the barrel.
Plus, I don’t think air pressure from a sealed barrel would have the resistance to stop the momentum of a bullet. How compressed does the air have to be to balance the explosion force? By then the bullet is going so fast, it will penetrate a normal metal-covered door. The compressed air in front just reinforces the shock to burst the steel cladding. The bullet has accelerated for say, 6 inches of the barrel and you expect it to stop due to compressed air in front in 1/20th of an inch?
In retrospect I think you are correct. The bullet slows down a little as pressure builds up, but even a rapid decrease in pressure behind it won’t slow it down much because of the momentum of the bullet and gasses.
The Mythbusters tested the old “Finger in the shotgun” bit. Even welding a steel plug on the end didn’t cause the barrel to explode, just bulge out.
I would think the ‘weakest’ would be the strength of the human hand holding the gun against the door. Wouldn’t the increased ‘kick back’ be enough to force the gun back at least an inch or two from the steel door?
FWIW, typical pressures within a shotshell after firing are in the 11-13,000 PSI range. Typical pressures for centerfire rifle cartridges like 5.56 x 45mm or 7.62 x 51mm are in the 55-62,000 PSI range (5.56) or 60,000-ish PSI (7.62)
That kind of pressure can and does break things when the barrel gets obstructed. This is a link to an older thread here on the Mythbusters claim, and it has this picture of an exploded rifle barrel. (There are others easily googleable; I just thought using an older thread’s picture from here was funny.)
Centerfire handguns can have the same sort of thing happen. Glock Ka-Boom! is a colloquial term that describes the phenomenon in Glock pistols. SAAMI pressure for 9 x 19mm is 35,000 PSI, per the wiki. For .40 S&W, where many of the Ka-Boom complaints originated, the SAAMI pressure is 35,000 PSI.
EDIT: Moreover, the volume within a wider, longer shotgun barrel is going to be greater than the interior volume of a shorter, narrower rifle barrel. If the barrel obstruction for the shotgun is at the muzzle, all of that 11,000 psi gas within the shotshell has the entire barrel to expand into. I’ve not done the math, but I can see the pressure being much lower for the shotgun barrel versus the rifle barrel, even if hypothetically they started with the same chamber pressure.
Not much more than the kickback from the gun held in the open. You can’t hold it against that pressure, air is easily expelled around the almost instant separation between the door and the barrel then the explosion gasses follow the bullet through the hole in the door (assuming the type of door I mentioned above).
I would still think that the shell enters the barrel from the back - the mechanism that ensures the shell does not eject backward (even partly) and hence shatter would not be designed for the blowback forces from a totally obstructed (welded closed) barrel, unless it’s one of those bolt-action rifles.
(But yes, just holding a barrel against the door I suspect the weakest link is the hand.)
Depends on the firing mechanism of the gun. Some classic automatic pistols of the 20th century (like the Soviet Makarov) worked on plain blowback like submachine guns usually did. In a plain blowback weapon the bolt does not lock. Its inertia just limits its movement backward until the pressure in the (typically low powered) cartridge case drops enough for the case not to explode as it ‘blows back’ out of the chamber. If you block the barrel the bolt still flies back but a lot harder perhaps to where it breaks loose, and the cartridge case probably also explodes.
But most automatic pistols work on the short recoil principle (like the M1911) where the bolt is positively locked on firing. The barrel recoils a short distance relative to the receiver unlocking the bolt and throwing the bolt/slide back further via some kind of mechanical advantage. If you weld the barrel to a door and fire the gun it won’t cycle at all, bolt remains locked, cartridge case still supported all around by the chamber, so something else, if anything does, would have to give way.
As somebody else mentioned, in the normal operation of a revolver some propellant gas escapes between the front of the cylinder and the rear of the barrel. More would if you blocked the barrel.
Among those three a recoil operated automatic pistol would be the most likely to explode if you blocked the barrel. What exactly happens I guess depends on the particular design of gun, how powerful a type of ammo (for example .357 Magnum revolvers can fire .38 Special, stressing the gun much less, automatics are typically designed more for a particular cartridge type) and how exactly you block the barrel. Somebody mentioned a pistol barrel just bulging to let the gas by if plugged, but presumably that was with just an interference fit of a plug hammered into the barrel. If the obstruction is all-around welded to the end of the barrel it seems the barrel might fail rather than the weld.
I wouldn’t do this either.
When you state [opens fire] i hope you really mean “Fire a shot” or “touches one off”,
Opens fire has a connotation that you are planning on shooting a series of shots?
The simple answer is; No one knows for sure what is going to happen.
But think of it this way,
When you pull the trigger on a firearm you are holding the launching equipment for a rocket!
If the energy cannot go forward of the launch equipment then that equipment will want to go the other way, in fact even wen it goes in the way intended it still goes the other way and we interrupt that by holding firmly as we absorb the recoil.
Here are some pictures of KaBooms that i have collected of have access to in over 30 years teaching Firearms Safety.
1 DA Revolver, over charge of propellant(Powder)
2Break Action 20 Ga Shotgun, 3 inch shell forced into a 2 1/2 inch chamber.
3Mauser 12 ga. shotgun, Barrel entered water when crossing creek in below zero (F) freezing some water in bore.
4 Collection Board of destroyed barrelscaused by barrel Obstruction.
5 Parker Hale (K98 Mauser) .270 win unintentionally loaded with a .30-30 Win Cartridge.
In background a Ruger MKII Model 77 7MM Rem Mag loaded with 7mm-08 Rem cartridge.
6 Cartridges involved in Ruger incident. Shooter did not know difference between 7MM cartridges and loaded rifle with wrong ammunition for this rifle. Look at these examples and see evidence on what was done. When one of the wrong cartridges went off the case formed to seal the chamber but ruptured and the bolt was rotated open by the GAS and the shooter got a face full of burning powder, the magazine floor plate was blown open, Stock cracked. The bullet cleared the barrel. Only permanent injury to the shooter is un-able to not flinch!
And the picture of the Mossberg Model 10 with the classic Banana Peel happened when a Laser bore sighting device was inserted into a loaded rifle and the shooter pulled trigger on a “supposed” unloaded rifle.