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Old March 30, 2020, 05:54 PM   #1
Derringeer
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How strong are cartridges?

When a brass cartridge is ignited, it expands into the walls of the chamber. If a cartridge would be ignited outside of the chamber, it would blow up. In a chamber where the cartridge isn’t fully supported it cracks.

So my question is, what would happen if you made a oval chamber that could take multiple rounds stacked together on top of eachother? Would they still blow up at the weakest spots which are in-between them, or would the geometry make them hold up better?

Here’s a picture that describes what I mean, seen from behind (each number represent a round, in this case it’s 3 rounds, so the yellow area are rounds/brass and the grey are is the steel chamber)
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Old March 30, 2020, 06:28 PM   #2
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A cartridge ignited outside of a chamber does not blow up. The brass is just forced to separate from the bullet.
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Old March 30, 2020, 06:37 PM   #3
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Well when a primer is detonated it ignites the powder to burn. That burn is very rapid but not an explosion. The pressure from that burning powder pushes outward in all directions at the same time and rate. This causes the brass to expand. The expansion is stopped by the walls of the chamber, and the rear of the breech, which directs all the pressure forward against the base of the bullet and so "bang".

After the expansion of the brass some retraction also occurs. This is what allows for simple extraction.

When a bullet is ignited outside a chamber and not limited by any surrounding walls the case expands rapidly to it's limits and may crack at it's weakest point. This diverts alot of the pressure away from the base of the bullet. The bullet will essentially drop from the case with little forward energy. The base of the case has nothing behind it. So the case is almost as much blown away from the bullet as the bullet is thrown out of the case. Possibly more depending on the weight of the bullet.

So in the one on top of the other design you have above. Do all the rounds go off at once, or one at a time?

With no walls between the rounds the cases would expand more into the case below, or above it, tending to stick. The whole operation would be dirty with fouling as well. Extraction could be an issue.

There is a reason no one has built a design like this.

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Old March 30, 2020, 06:39 PM   #4
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Schlitz 45 It’s true, atleast regarding smokeless powder which need pressure to burn fast and generate high pressure. But in my scenario, the pressure is generated inside of the cartridge since there is a barrel infront of it, so the bullet can’t escape. Compare it to a chamber cut in half with a barrel that the bullet is forced into, then the case will explode.

However, in my example the chamber isn’t cut in half like that, so the cartridges are more supported, both by the chamber and the other cartridges. So my question is if the pressure will give enough focus on the small area along the cartridge that the steel chamber isn’t supporting to blow it out, and how much strength will the supporting cartridge beneat give to prevent that?
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Old March 30, 2020, 06:49 PM   #5
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The cartridges are ignited one at a time. Here’s another version which require even less support of the chamber
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Old March 30, 2020, 06:53 PM   #6
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The brass would expand into the open area beneath or above the case. Depending on the pressure of the round that would be more or less pressure.More or less potential expansion of the brass case.

For the top and bottom round the case would expand as normal except for the area below, or above it where there is no steel wall to contain the expansion of the brass. That brass would expand into the brass below it or possibly crack.

For the center round the brass would expand both above and below.

Some velocity would be lost. Some fouling as well. That would be more or less depending on the width of the gap in the cylinder walls between rounds.

Extraction and fouling could be an issue.

Again is the plan for the rounds to fire one at a time or simultaneously? OK I see you said one at a time.

Also, why?

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Old March 30, 2020, 06:54 PM   #7
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Quote:
Originally Posted by Derringeer
When a brass cartridge is ignited, it expands into the walls of the chamber.
Correct. (Well ... sort of)

Quote:
If a cartridge would be ignited outside of the chamber, it would blow up.
Incorrect.

Quote:
In a chamber where the cartridge isn’t fully supported it cracks.
Incorrect.


Quote:
Originally Posted by Derrigeer
Schlitz 45 It’s true, atleast regarding smokeless powder which need pressure to burn fast and generate high pressure. But in my scenario, the pressure is generated inside of the cartridge since there is a barrel infront of it, so the bullet can’t escape. Compare it to a chamber cut in half with a barrel that the bullet is forced into, then the case will explode.
In other words, you are on a firearms forum asking a question about something that is a bomb rather than a firearm cartridge.

Does that about sum it up?
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Old March 30, 2020, 07:03 PM   #8
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Wait? I just looked more at the second pic.

There is blessed little support for the rounds. So it's likely the cases of all three would rupture and the bullet leave the barrel at greatly reduced velocity and ridiculously poor accuracy over any distance. You'd also have to clean every chamber thoroughly before another round could be loaded. Extraction could be tough, as well.

Does it have three separate barrels?

Is this still a gun? What would the point be?
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Old March 30, 2020, 07:13 PM   #9
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Well, I’m experimenting with something as odd as a ’magazine’ for a superposed muzzleloaded gun.. Actually the cartridges isn’t only cartridges inside of a chamber, in this case they are whole barrels themselves.

I’m seeking for a solution that will allow a design like this. Ordinary thin brass cases wouldn’t give enough strength I guess, but since the ’cartridges’ will support eachother they still don’t need to be as strong as a barrel made of steel that can handle the fire on its own, if that make sense..
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Old March 30, 2020, 07:21 PM   #10
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A variation of this:

https://www.youtube.com/watch?v=pRMm-oUq4nc

Or this?

https://www.youtube.com/watch?v=WWGII108sOU


https://www.youtube.com/watch?v=MDYtxxRU_cY
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Old March 30, 2020, 07:40 PM   #11
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I use the same superposed concept as the first pistol does, but I only load two loads in the barrel instead of four (because of overcompression caused by recoil), and instead of a flintlock mechanism I use electric igniters to ignite the gunpowder..

The idea is to make a hybrid of the ”ratchet pistol” and the ”howdah pistol” basically, but instead of a set of preloaded barrels as magazines I thought about making preloaded ’cartridges’/thin barrels that could be inserted into a main barrel, making it more practical..
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Old March 30, 2020, 07:51 PM   #12
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Quote:
Originally Posted by Derringeer
Well, I’m experimenting with something as odd as a ’magazine’ for a superposed muzzleloaded gun.. Actually the cartridges isn’t only cartridges inside of a chamber, in this case they are whole barrels themselves.

I’m seeking for a solution that will allow a design like this. Ordinary thin brass cases wouldn’t give enough strength I guess, but since the ’cartridges’ will support eachother they still don’t need to be as strong as a barrel made of steel that can handle the fire on its own, if that make sense..
It makes no sense at all. In a previous post YOU wrote:

Quote:
But in my scenario, the pressure is generated inside of the cartridge since there is a barrel in front of it, so the bullet can’t escape.
If the bullet can't escape, you don't have a firearm. The purpose of a firearm is to expel a projectile. If the projectile (the bullet) can't escape, you don't have a firearm ... you have a bomb.

Your explanations are also extremely confusing as to what's a barrel and what's a chamber. Again, with all due respect, nothing you have presented makes any sense to me so I can't be of any help to you.
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Old March 30, 2020, 07:59 PM   #13
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I think you are making a fundamental mis-assumption.

A cartridge SEEMS to detonate but what really happens is that it doesn't blow UP so much as blow OUT.

And, the amount of the effect varies with the amount of pressure. In some cases, low pressure rounds simply have the case "pushed" back off the bullet (the case is lighter), and as soon as the separate the pressure is vented, and the sometimes intact case comes to rest a short distance from the bullet which may not have moved, at all.

At higher pressure levels, the brass reaches its strength limit before getting free of the bullet and ruptures (cracks / splits) sometimes at more than one point. And, at centefire rifle pressures the case can fragment SIMILAR to a grenade in appearance, but in a random manner.

When a case is partially supported the unsupported area is what usually lets go.

In your first drawing, with the rounds in contact with each other along a narrow area, it is very likely that the first round to fire will split where it is only "supported" by the other case. The other brass cases are no where near as strong as steel. So, the first round splits and high pressure gas "vents" against the unsupported body of the next case, possibly crushing, deforming it, possibly detonating that powder charge and creating a cascade effect of all rounds detonating sympathetically.

Something like this is what "killed" a lot of tanks in WWII. A hit in an ammo storage rack setting off the powder of one or more rounds and that setting off multiple others, with the resulting large explosion "killing" the tank and often the crew.

I think with anything above the very lowest pressure levels your multiple "partial chamber" gun would detonate all powder in it in an uncontrolled manner. Dangerous, almost certainly.
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Old March 31, 2020, 07:49 AM   #14
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Since you are planning this as a muzzleloader, you need to study cap and ball revolvers. If loaded improperly, a cap and ball revolver can ignite adjacent cylinders simultaneously when the chamber aligned with the barrel fires. It's not good for the gun, or the shooter.

When loading from the muzzle you have no way of positively sealing the separate charges from each other. It will chain fire from one charge to the next. The pressure involved forces burning gas between the steel / brass and the bullet in the adjacent positions in the "magazine", thus igniting the powder charge.

Because you have removed the complete circle of steel around the chamber, it leaves a weak spot in the steel. The magazine area will likely expand to the point of failure as all of the charges ignite nearly simultaneously.

Think about the warnings you have received here before you pull the trigger on this one.
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Old March 31, 2020, 08:41 AM   #15
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Absolutely FALSE. I have 7 stitches in my arm, from a cartridge going off in my reloading press trying to seat a high primer. A piece of the case a little smaller than a dime was remover from my arm along with a $2,000 ER bill

You can find the post in the reloading section with regards to seating high primers post #3 dated 7/15/17
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Old March 31, 2020, 12:02 PM   #16
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Don P, please clarify what you are saying is absolutely false. Without that clarification, it appears you are saying that what big al hunter said is false, and I doubt that's what you meant.
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Old March 31, 2020, 12:19 PM   #17
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I was referring to post number 2. I tried to post the links to my photos and post from the reloading thread without success. I am making no reference to a muzzleloader. Mal if you could link up the photos for me from the thread I would Appreciate it.


[Edit by Mal H]
Here is the post with the images of the injury:
https://thefiringline.com/forums/sho...89#post6491089

The first image looks like a thumbnail image, and not the regular sized one.
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Old March 31, 2020, 12:26 PM   #18
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DERRINGER- To me, it sounds like you are a future organ donor
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Old March 31, 2020, 12:45 PM   #19
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Too many variable to give any useable answer. Different cartridges have different brass thickness, various pressure levels, varying bullet weights, etc. Pressure will always seek out the path of least resistance.

If you use thick enough brass and low enough pressure it'd be easy to create something that pushes the bullet out the barrel without igniting the 2nd cartridge.

Are you making the cases yourself?
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Old March 31, 2020, 04:19 PM   #20
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I still don't understand the point of making a firearm that doesn't allow a bullet to leave the barrel.

Quote:
Originally Posted by Derringeer
But in my scenario, the pressure is generated inside of the cartridge since there is a barrel infront of it, so the bullet can’t escape.
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Old March 31, 2020, 06:19 PM   #21
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Quote:
When a bullet is ignited outside a chamber and not limited by any surrounding walls the case expands rapidly to it's limits and may crack at it's weakest point.
I suspect the powder would ignite way before the bullet would ignite...
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Old March 31, 2020, 08:16 PM   #22
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Quote:
When a bullet is ignited outside a chamber and not limited by any surrounding walls the case expands rapidly to it's limits and may crack at it's weakest point.
I suspect the powder would ignite way before the bullet would ignite...
Well, yeah.

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Old April 1, 2020, 06:17 AM   #23
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Quote:
The first image looks like a thumbnail image, and not the regular sized one.
Correct and thank you for posting the link for me. Resizing photos at time are challenging for me. I know just enough to really reek havoc on a computer and have difficulty doing what some folks do in a snap.
Back to the thumb nail, wound channel from the shrapnel was roughly 3 inches in length and scare is about 1 1/2 inches long. I have the case and piece of brass removed from my arm as well as a picture of the stitches in a shadow box at my reloading bench as a reminder.
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Old April 4, 2020, 02:14 PM   #24
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Here is the explanation and pics of the gun that folks here (everyone I believe) said was a disaster waiting to happen...

https://thefiringline.com/forums/sho...d.php?t=606411

"Why did my gun blow apart?"

You weren't making a gun but some type of potential pipe bomb.

You need to learn some about materials, gun powder, etc.

I think maybe this thread should be closed as well.

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Old April 4, 2020, 02:29 PM   #25
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I can’t answear in the other thread so I’ll answear here instead..

I always test fire my experiments remotely, and I like to make them with weak materials sometimes because if I make a design that do hold up when it’s done weak, I know that the design is strong for that caliber and load. If it hold up with JB-weld for example, even when it’s fired with proof-rounds, I know that it will hold up even better if it’s welded.

The barrels themself are very strong for the black powder loads I use, so they won’t blow up.

Is the issue here the breech-hole? why doesn’t the recoil prevent the barrel from flying forward?

I made these pepperbox style guns: https://imgur.com/brxeUKY with basically the same concept as the gun that blow apart, with electric igniters inserted through a 0.05” inline hole in each breech of each barrel. Here’s some more details of the inside and the making of the ”receivers” of these guns: https://imgur.com/MMmU9ax https://imgur.com/OX8o4NC https://imgur.com/W9chvSl I haven’t had any issues with those yet, how come?

This is an earlier single shot derringer that I made https://imgur.com/gJgqjXD, it doesn’t have a hole in the breech but through the side like a classic muzzleloaded cannon, the barrel holds in place with magnets - and it works since the recoil is forcing the barrel/cannon backward and not forward.

Based on the guns above that is functional and other guns like this one https://youtu.be/J2tV-dsvPlg I still think it’s weird that the tiny hole in the breech was able to propell the whole barrel forward.. Compare it to a slamfire shotgun, that have the whole breech open.

Let me put it this way, if you would make a receiver to this particular gun that I’m working on right now, that blow apart, how would you design it? I’d like some input. The goal is to make a strong receiver that allow the ”barrel-packs” to easily be replaced, since the barrelpacks will act like magazines.

Last edited by Derringeer; April 4, 2020 at 02:55 PM.
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