Bore obstruction and pressure questions.

[Bazoo]

I want to understand what happens when you have a bore obstruction and it blows your gun up.

So let’s say, a 30 caliber rifle. 30-06 for thought experiments sake. If you left a cleaning patch in the bore, say 3-4” from the chamber, and fired a round, it would blow the barrel up correct? Would it blow at the spot where the obstruction was? What kind of pressure would it make? Would it cause a higher pressure than a solid obstruction? What would the pressure curve do?

What if the patch was just at the muzzle? Would it still blow the barrel? Why wouldn’t the air in front of the bullet push the patch out?

What if you had a bore obstruction, and shot a blank to remove it? Would it blow the barrel? Would it just bleed off?

Im glad to read articles or info if anyone can offer them to this subject matter. I’m not interested in YouTube videos of people blowing up their guns. I am interested in the science as to what happens.

Bazoo

[reddog81]

There are many variables that would have to be known in order to give any answer. It would depend on the size of the cleaning patch and how wedged in the barrel it is. I would be willing to bet any normal sized cleaning patched that was accidently left in the barrel would be blown out and you'd never know the difference other than poor accuracy with that shot. The column of air in the barrel in between the bullet and patch would start pushing the patch once the bullet starts moving. Think of a piece of paper in a straw. you can blow it out with ease. A wad of a dozen patches stuck in the barrel might cause a problem or maybe not...

Pressure is going to find the weakest spot. As long as it's easier to push the patch out that is what will happen. The barrel is not going to blow unless the force to split the metal is less than the force to dislodge the patch.

[gwpercle]

My friend stuck a cleaning patch in a 22 LR bolt action rifle .
He thought he could clear the patch out by firing a round ... he did and right about where the patch was stuck ... the barrel ringed itself ... very nicely , you could even see the ring on the outside of the barrel . He got the patch out but he ruined the barrel ...and this was just a 22 LR ... I would in no way shape or form try that with a 30-06 ... I'm thinking something bad is going to happen !
Sorry about the lack of science but John isn't a scientist and I barely made it out of school ... all we got is experience and a ringed 22 LR barrel .
Gary

[Hick]

Hatcher's notebook has a chapter on this-- lots of interesting experiments

[rbuck351]

I suspect it is the bullet hitting the obstruction causing the obstruction and the bullet to expand and either ringing the barrel or rupturing it. I think a patch in the barrel may or may not rupture the barrel depending on several things like weight of patch, how stuck, pointy bullet may wedge the patch out more than a wadcutter type bullet, speed of bullet when it hits the patch, weight, hardness and shape of bullet and a bunch of things I haven't thought of.

I don't think the pressure behind the bullet has as much affect as the impact speed of the bullet as the damage seems to be at the point of impact. Nothing scientific, just my thoughts.

[BJK]

Interesting thoughts. I hope to never have first hand knowledge.

[wv109323]

Like everyone said there are too many variables to answer your questions. The weight of the patch has to be accelerated to the speed of the bullet for no damage to occur. That is not going to happen because the patch is not seeing the pressure generated by the burning powder. The time a bullet is in the bore after powder ignition is microseconds. The life of a barrel is only about 15-20 seconds of actual bullet travel time
So think of a speeding train headed down the tracks with another setting idle ahead of it. There is going to be a collision.

[john.k]

I remember my brother shot a stuck patch out of a 222.......put a massive bulge near the muzzle,but nothing blew up......so out came the hacksaw and he had a 17" barrel before the old man found out about it.

[contender1]

As noted,, too many variables to give specific answers.

I have a blown up frame of a Ruger Super Blackhawk .44 mag I bought to use in my classes. I have seen several other cases where guns were damaged or blown up by various issues. How about an Ingram MAC 11 in 9mm with 11 bullets stuck, end to end in the barrel,, BEFORE it blew the bolt & action apart? First one was a "squib" followed by others stacking behind it in this full auto.

As noted above,, pressure finds the weakest point to escape.

Sometimes it can happen w/o damages, other times, minor damage, & other times,, major damages to include injuries to the shooter. So, to try & understand what happens,, look for the weakest point for pressure to escape.

[Burnt Fingers]

Like everyone said there are too many variables to answer your questions. The weight of the patch has to be accelerated to the speed of the bullet for no damage to occur. That is not going to happen because the patch is not seeing the pressure generated by the burning powder. The time a bullet is in the bore after powder ignition is microseconds. The life of a barrel is only about 15-20 seconds of actual bullet travel time
So think of a speeding train headed down the tracks with another setting idle ahead of it. There is going to be a collision.

That would be a very long-lived barrel. Most centerfire rifle barrels have a true life span under 5 seconds.

[woody1]

You can shoot out a stuck boolit just don't use a bullet or a boolit. I would not use a blank either unless it was a crimped blank. Just load a cartridge sans bullet, barrel pointed up, and fire. I have done this several times with no harm done. Let the flames begin!!

[fixit]

Woody, I'm not interested in flaming anyone, but I be worried about your well-being.... your bore clearing process will likely work until it doesn't. The processes behind bore obstruction explosions and SEER are not well understood, and can vary a thousand ways in a thousand events. I've known guys who would stick a shotgun barrel into the water to shoot at things in the water, and then scoff at the warnings given about blowing their gun up, and then here later about their gun having a split barrel from doing the same thing.

[Mk42gunner]

There is no way I would try to clear a bore obstruction with anything containing gun powder and a primer, especially if the projectile is included. Life is too short to see if a barrel will hold the pressure of a nominal 50,000 psi load (in a clear barrel) that is being now fired with an obstruction.

I remember one time one of the visiting Helo squadrons brought in an M-60D barrel that had an M-80 ball projectile stuck about 3-4" into the bore, (the case had blown out). It took a close fitting steel rod and several fairly heavy blows with a three pound hammer to get it out.

Robert

[GL49]

Interesting question. I've often wondered if the advice of putting a piece of electrical tape over the muzzle to keep out debris and rain in the winter was a good idea. Not taped to the barrel, just a small chunk stuck onto the face of the muzzle. One of my buddies said to get one of those foam earplugs, roll it up and insert it in the muzzle about half the length of the earplug. The earplug doesn't sound like a good idea, I don't know about the tape?
Any input from anyone who's done this?

[Electrod47]

Interesting question. I've often wondered if the advice of putting a piece of electrical tape over the muzzle to keep out debris and rain in the winter was a good idea. Not taped to the barrel, just a small chunk stuck onto the face of the muzzle. One of my buddies said to get one of those foam earplugs, roll it up and insert it in the muzzle about half the length of the earplug. The earplug doesn't sound like a good idea, I don't know about the tape?
Any input from anyone who's done this?

An ear plug becomes a BOREPLUG how is that a good idea?

[Wilderness]

You can shoot out a stuck boolit just don't use a bullet or a boolit. I would not use a blank either unless it was a crimped blank. Just load a cartridge sans bullet, barrel pointed up, and fire. I have done this several times with no harm done. Let the flames begin!!

Observed a more controlled variation on the above - a patch stuck in a shotgun. A primed case failed to move it. Same plus a grain of black powder .... can't remember the success point but it was in the 1-3 gns range. Moral: Build up slowly.

My understanding of barrel bulges is that they occur when a pressure wave hits the obstruction, like chamber ringing, and that the ring will be immediately behind the obstruction where the pressure wave is arrested and diverted outwards. If the pressure is low enough (e.g. a primer and a very small amount of powder) the steel can cop it and the ring doesn't happen. It's anybody's guess what a full charge of powder (without bullet) or a blank might do when an obstruction is encountered.

[BunkTheory]

there are innumerable destruction tests online, in video and text form.

People have managed to have rifles blow bullets out of a barrel by firing a live round. typicall .308 bullets lodged in the bore of a mosin 91/30 and at MOST ringed the barrel. Have seen results of ishapore 7.62 enfields that had bullets lodged in bore, and military surplus fired..

In the olden days of the renessaince the standard was a round ball seated with a patch upon a barrel filled 2/3rds with black powder. A musuem/armoury did their own tests with that, and discovered that the 2-400 year old guns they did that with perhaps 10% failed in the retest.

Historical note, the powder used was the historical accurate 4 fg grain size for main charge.

[DougGuy]

I keep a 3' piece of 1/8" drill rod ringed with tape every 8" or so, JUST to push through the bore and make SURE there is no obstruction. Actually this is for the air guns, to make certain there isn't already a pellet pushed into the breech before I load another one. Not that it would blow up the gun but this is a pest control tool that I need moment of squirrel's noggin accuracy and double pellets don't give me that.

[rbuck351]

Tape over the end of a barrel is fine. It is outside the barrel so when the bullet hits it the force going sideways has nothing to push against except the tape. I used it all the time when hunting from snowmobiles in AK. I had a Rem 700 7mm mag that split the barrel from the front back to just ahead of where the tipof a loaded round would be. I think it was a bit of snow or ice in the end of the barrel from riding through snow covered brush. After that I used tape which just blows apart upon firing. I would not use anything inside the barrel, even an earplug.

[Buck Shot]

Someone once asked me what I thought would happen if he tried to shoot an AKM underwater (with bore filled with water). I said it would blow the barrel, he said no it wouldn't, and we went round and round on it. Then he found a video of some lunatic who took an AK with him into a swimming pool and fired it with the barrel filled with water...and it didn't blow up. This was almost unbelievable to me, but what really must have been unbelievable was how LOUD that must have been with your ears underwater!

I've used elec tape over the muzzle of my 270 to keep rain out while deer hunting (only because I read that it was OK to do in a trustworthy publication) but I forget whether I've ever actually fired the gun with tape over the muzzle...

[gwpercle]

Someone once asked me what I thought would happen if he tried to shoot an AKM underwater (with bore filled with water). I said it would blow the barrel, he said no it wouldn't, and we went round and round on it. Then he found a video of some lunatic who took an AK with him into a swimming pool and fired it with the barrel filled with water...and it didn't blow up. This was almost unbelievable to me, but what really must have been unbelievable was how LOUD that must have been with your ears underwater!

I've used elec tape over the muzzle of my 270 to keep rain out while deer hunting (only because I read that it was OK to do in a trustworthy publication) but I forget whether I've ever actually fired the gun with tape over the muzzle...

I must have read the same magazine ... it also said if you shot with the tape on the muzzle , nothing would happen , the tape is simply blown off or to the side ... it doesn't have enough grip on the tape to resist the muzzle blast ... at least regular electrician's black plastic tape of the old day time ... not any modern super sticky Gorilla Tape that you can mend leaking water towers and Concrete Dams with ... that Super Dooper Tape might do damage !
Gary

[blackthorn]

Plus one on the fire primer only, then +1 Gr.at a time till it moves the obstruction. Ever since I watched a guy push a 6" branch out of his barrel at the end of a days hunting, I have used electricians tape over the muzzle for many years to keep stuff out of the barrel. There is even a "muzzle condom" sold for the same purpose.

[rbuck351]

Actually the electricians tape does have the grip to resist the blast but the part over the muzzle shreds leaving the tap stuck to the outside of the barrel. I have used it a lot and I use two pieces crossed over the muzzle and then another piece around the muzzle to make sure the tape isn't knocked off while busting through brush. I haven't tried it but I would bet any type of tape over the end of the barrel would be fine because anything outside the barrel will not go back inside the barrel to expand it to the bursting point.

[Mr_Sheesh]

In a pinch a "finger cot" might work but those are getting kind of thick compared to plain electrical tape.

[Bazoo]

Pretty interesting. Thanks for the input here.

[farmbif]

on swapping and selling recently there was a pistol barrel that was blown ou/expanded at the end, wonder what caused it. years ago I picked up a beautiful 11-87 for cheap. the barrel had a bulge right where the choke tube seats, what happened? never a problem with new remchoke barrel. I'm guessing-operator error?

[Harter66]

There are lots of shot guns with rings of varying degrees from stuck wads . Most were plastic wads and duck guns . I would imagine that many were from assorted case failures and "wad cutters" or scored cases . A few water beads in a 12 ga barrel will stick a case . Experience only here .

I would think that a cleaning patch either within 2" of the muzzle scaled appropriately for 24" barrels or touching the bullet with an FMJ or non expanding solid would escape with minimal injury .

Springfield Armory did testing circa 1925 and determined the barrel life of an 03' 06' was 30 seconds , or 10,000 rounds of standard Caliber 30 Model of 1906 M2 Ball from standard lots of issue ammunition . That's 10,000 round at approximately .007 seconds dwell time within the barrel . (Pardon decimal errors , recent concussion and pain meds a 7' fall and broken stuff will do that)

[Bazoo]

More interesting replies. Thanks to you both.

Harter, could you elaborate on the water beads? Do you mean water in the chamber will stick a case with hard extraction? Or do you mean pressure causing hard extraction?

[JSnover]

You can shoot out a stuck boolit just don't use a bullet or a boolit. I would not use a blank either unless it was a crimped blank. Just load a cartridge sans bullet, barrel pointed up, and fire. I have done this several times with no harm done. Let the flames begin!!
I've done it with a revolver, all it took was a primed case.

[JSnover]

Someone once asked me what I thought would happen if he tried to shoot an AKM underwater (with bore filled with water). I said it would blow the barrel, he said no it wouldn't, and we went round and round on it. Then he found a video of some lunatic who took an AK with him into a swimming pool and fired it with the barrel filled with water...and it didn't blow up. This was almost unbelievable to me, but what really must have been unbelievable was how LOUD that must have been with your ears underwater!
.
Years ago I remember reading about firing a 1911 underwater. As I recall, the effective range was something like 10-15 feet. I don't remember any comments about damage to barrel.