Talk:Internal ballistics

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[edit] Article becoming book

Seems to me, this article might be getting close to a Wikibooks project. - dcljr 03:12, 6 Nov 2004 (UTC)

Yeah, it does seem to keep growing. I need to fiddle around a bit more with the internal ballistics software--I wrote it 10 years ago and pulled it off an old backup so I could add graphs. There are some very interesting interactions that happen at the very beginning of the pressure curve, and I need to add an initial pressuer spike to cover the detonation of the primer. I'd also like to modify it to allow multiple powders with different burn rates to see how that impacts the pressure curve--a task that is too chaotic for amateur experimentation with real cartridges. Of course, publishing the results (which would lead to a pretty significant amount of new data) could be risky, as it is a very chaotic system and anyone who decided to try it out could well blow up a gun and injure themselves. Given the litigious nature of today's society, publishing such information seems risky. All the reloading books warn against trying this, since without really expensive pressure measuring equipment you can't really see how close you are to dangerous pressure levels. --Fluzwup 23:11, 17 Nov 2004 (UTC)

I removed the headlines at the end that hadn't been filled out with text. There is still some work that needs to be done though; it needs to be much shorter (possibly split up into a wikibook and a shorter article), and it could use some references and external links. --83.250.217.93 13:00, 6 Jun 2005 (UTC)

[edit] Energy and recoil operation

This note: editor's note: kinetic energy = mass * velocity^2 So cutting the mass in half means the velocity has to be increased by only 1.414 times. Not being a firearms designer, I can only correct the physics. Still, I think the assumption stands was added to the section on recoil operated designs. I changed the text from "energy" to "recoil" in an attempt to remove the assumption that caused this note to be added. Recoil operated firearms depend on the energy of recoil, which is based on m * v, not (m * v^2)/2. Cut the bullet weight in half, and you must double the velocity to get the same recoil, and the new lighter, faster round has double the kinetic energy as the heavier, slower round (since it's 2x as fast, but 1/2 as heavy, energy is changed by 2^2 / 2). scot 15:53, 16 February 2006 (UTC)

This is not always and everywhere true. There are a few recoil calculators online and they all show what should be obvious after careful thought. Recoil is due to two components. The first, as your formula indicates, is due to the mass of the bullet being forced in a given direction. The other component is the mass of the gas pushing the bullet down the barrel when it exits the barrel. For lightweight bullets, such as varmint loads, over half of the total recoil is due to the gas escaping at the end of the barrel. If you look at the end of an MG-42/MG3 you will see it has a feature known as a recoil amplifier. This is a funnel shaped cone which gives the gasses more surface at the end of the barrel to push back against. If this feature is put at the back of the barrel, such as in a recoilless rifle or cannon, like the Mauser RMK series, it counteracts normal recoil forces. Solidpoint 03:57, 14 March 2007 (UTC)

[edit] Performance & peak pressure

Even the most cursory glance at a load table will reveal the error of saying that higher peak pressures generate higher velocities. That is absolutely, unequivocally NOT true.

Anyway, I am trying to work through some of the text and try to sharpen it and make a correction here and there perhaps. Solidpoint 04:17, 14 March 2007 (UTC)

Hagerman, your BOT is a pain in the ass. I went through the bother of signing up on your tedious list of people this damned thing should NOT harass because I cut and past back and forth to Word to check spelling and grammer - so please F**ck off. Solidpoint 04:17, 14 March 2007 (UTC)

[edit] Aspect ratio

I always thought the optimal case would be tapered in a funnel shape away from the primer to provide a uniform distance from the primer to the powder. Do you have any support for your reasoning that a spherical shape is optimal? I'm kind of curious now Solidpoint 04:15, 14 March 2007 (UTC)

Short, fat cartridges are almost invariably more efficient; look at things like the .221 Fireball, the .308 x 1.5", and the super short magnums. These cases generate more velocity per grain of powder than their longer counterparts, and do so with a greater consistency. The problem with the reverse funnel (besides the fact that such a cartridge won't chamber in any but a front loading chamber) is that you don't have all the powder a consistent distance from the primer; the flame front still has to go from narrow to wide end, you're just putting the bulk of the powder further from the primer. This is likely bad; tests have shown more consistent velocities in overcapacity cases if the powder is allowed to settle to the rear of the case before each shot than if the powder is allowed to settle to the front.
Lets take the conical chamber and reverse it, so there's a sharp taper wide at the primer to narrow at the bullet; this is essentially the shape of a number of military cartridges such as the 8mm Lebel and the 7.62x39mm. The first thing Palmisano and Pindell did to the 7.62x39mm case was blow it out to cylinder with a VERY sharp shoulder--sharp enough it won't feed from a magazine, it's a single shot only deal because of that shoulder. However, the 6mm PPC is still one of, if not the most accurate cartidges in existance (I think about 50% of the top benchrest shooters still use it). If you look at the inside of the case, with the rounded web at back and the shoulder at the front, it's pretty close to an ellipsoidal shape. The current trend is to make that ellipsoid shorter and wider; keep that up and you end up with something roughly spherical.
I suspect, though I have no way to prove it, that a cartidge with a combustion chamber about as wide as it was long would proove to be about ideal; the problem is that this is impractical in high velocity, long range cartidges (the case diameter would be huge) and the rules for short range, low velocity target shooting are too highly restrictive to allow much room for innovation. I'll bet if you had a 50 yard benchrest division with no caliber restriction, you'd see a lot of people starting with the .45 ACP and working from that--load that with a medium burn rate powder designed for a rifle length barrel to get the load density up to 100% and I'll bet it would produce an amazingly consistent velocity. scot 14:41, 14 March 2007 (UTC)

[edit] Corrosive ammo?

"Military-surplus Berdan-primed ammunition is also often corrosive or slightly-corrosive, whereas Boxer-primed ammunition is often non-corrosive, although assuming corrosive or non-corrosive characteristics on the basis of whether Berdan or Boxer primed is never fool-proof."

I'm a gun noob, so this confuses me. It sounds kind of like something you might find in a SF story; acid bullets. I'm pretty sure that's wrong, but can't come up with any other explanation. Could someone explain? --StarChaser Tyger 02:52, 22 July 2007 (UTC)

Historically, gun powder (black powder) was always corrosive upon being fired. In the unfired state, black powder was not corrosive at all. So, a muzzle-loading, black powder, gun could be loaded and left in that state for literally years over the fireplace or wherever, until it was fired. Then, a gun shooting black powder always had to be cleaned the same day as it was fired, or else rust would set in on the next day. It wasn't the bullet that was corrosive; rather, it was the sulfur and nitrate compounds that were produced upon ignition of the potassium nitrate-sulfur-carbon mixture of black powder that, when mixed with moisture, would subsequently form weak acids, that in turn caused rust. Smokeless powder, which largely replaced black powder starting in the late 19th Century, is non-corrosive in nearly all modern formulations. Primers, though, are a varied lot. Some are corrosive, and some are not. Commercial primers are nearly always uniformly non-corrosive, for all modern ammo produced since about 1935. As it turns out, the primers that are the most reliable for use in combat over the greatest temperature extremes, while having the longest storage times, are nearly always corrosive. Likewise, Berdan priming is cheaper to implement on a per cartridge cost basis than Boxer priming. Hence, in many military-surplus rounds, where the lowest cost and highest reliability are desired per round, the rounds are often Berdan primed for reducing the cost per cartridge, and are corrosively primed, to increase the reliability of a cartridge firing properly under widely-varying environmental conditions. So, it is not about shooting acid bullets. Rather, it is about the compounds contained in the primer that, upon ignition, are often slightly acidic, or that, when subsequently mixed with water absorbed from the air, become slightly acidic. A common trick often used by weekend-warriors at the gun range is to use a window cleaner containing ammonia (e.g., Windex or similar) that is squirted down the barrel to neutralize the acid from the corrosively-primed mil-surp ammo, to stop the corrosion from eating away at the rifling of the barrel until the gun can be cleaned properly later that day, at least when firing cheap military-surplus ammo. Otherwise, the rifling will often become less sharp as the corrosiveness works on the edges of the rifling in the barrel. The difference in cost per round between non-corrosive modern commercial ammo and mil-surp corrosive ammo is often as much as $1 a round versus $0.20 per round. This is enough of a difference that it pays to buy a bottle of Windex to use with the case of mil-surp corrosive ammo, and plink away :-) Yaf 04:35, 22 July 2007 (UTC)
A bit more, info, if you're interested in chemistry. Black powder is composed of potassium nitrate, sulfur, and charcoal in roughly a 75-10-15 mix. When burned, the potassium nitrate breaks down to release oxygen and nitrogen (the oxygen of which produces CO2 with the charcoal) and potassium carbonate and potassium sulfate. Potassium carbonate, the primary component of the soot (black powder burns to about 55% solids, which is why it's so smoky and messy) is the nasty part as far as the gun is concerned, because it is hygroscopic (it sucks water out of the air) and when wet, forms a strongly alkaline solution, which will corrode the gun barrel if not cleaned soon after firing--past personal experience has shown that letting the cleaning wait until the day after can be long enough to pit the surface of blued steel (I forgot to clean around the nipple, and it was humid). Corrosive primers are made from mercury fulminate, which is a primary explosive, meaning it can be readily detonated by shock or heat. In most ways it's an ideal priming substance, because it's stable enough to last for many decades without degrading, holds up to moderately rough handling, and is sensitive enough to be easily ignited by the firing pin. On the other hand, one of the combustion byproducts is mercury oxide, which was used in mercury batteries (now being phased out). In addition to being a toxic heavy metal (not much of an issue, since it's used in very small quantities) mercury oxide in water produces a galvanic reaction with metals, which, like the potassium carbonate, causes pitting and corrosion. The non-corrosive replacements, lead styphnate and lead azide, produce non-corrosive products when burned, though they also contain heavy metals and should not be used in poorly ventilated areas. The newest primers are both non-corrosive and contain no heavy metals, using a tetrazene based substance. There are concerns, however, about it's sensitivity and shelf life when used in primers. scot 14:02, 23 July 2007 (UTC)
Thanks both of you for those thorough and well explained answers, that themselves deserve a page. --StarChaser Tyger 07:21, 24 July 2007 (UTC)
Interesting thought. I'm not sure that's quite worthy of an article in itself, and it's tangential to internal ballistics and so not really appropriate here. Cartridge (firearms), percussion cap (which also covers primers), gunpowder, and smokeless powder are all relevant, but they each cover only part of the issue. I think the logical place would probably be a section in ammunition on corrosive vs. non-corrosive ammunition, and then maybe create corrosive ammunition and non-corrosive ammunition articles that link to that section. scot 13:51, 24 July 2007 (UTC)
Heh. Mostly, I meant the size and level of detail. Far more than I was really expecting (something along the lines of 'One kind of gunpowder produces chemicals that can corrode barrels if they get wet'), and a lot of details... If the terms were in more common use, those two posts (slightly edited) would be pre-made articles for them... --StarChaser Tyger 10:15, 27 July 2007 (UTC)


[edit] Article too long

I have not read it all ! And I believe not many people does. It is certainly a good content but to me, it is far to long to provide a good overview of this subject. The kind of overview we are expecting from an encyclopedia. I think we should restructure in a way that each sub-chapters here be linked from an "internal ballistics" overview page.

Since I am new on the project, I just don't know how we could do that ? May be a way is to propose a draft page somewhere ? I don't know.

--Mdeby (talk) 00:00, 29 December 2007 (UTC)

The article length is just fine. The information really can't be condensed much. There are sub-articles for lots of these items and the items themselves are mere overviews. --Asams10 (talk) 01:52, 29 December 2007 (UTC)

Thanks for your reply Asams10.
It seems to me that the description on this page, at least the beginning and the end, is more related to "Small arms technology" than to "internal ballistics". Internal ballistics is more related to the "behaviour" of the bullet (and to a lesser extend of the gun itself) while the bullet is in the barrel. For example in the article, I think the Ignition chapter should summarize briefly the ignition phenomenon itself and its impact on the cartridge, pressure rising, delays, etc. But the priming methods that are thoroughly reviewed here, I think it should be linked to the article "Explosive primer" instead. The same for propellant. This is really good content but it is more related with "propellant technology" than to internal ballistics. It starts to talk about internal ballistics in the "Friction and inertia" chapter. Then, below from chapter "Accuracy and bore characteristics" to the end, it is again technology. Roughly speaking I would say:

Matchlock : Priming history
Wheel-lock : Priming history
Flintlock : Priming history
Caplock : Priming history
Rimfire : Type of cartridge
Pinfire : Firing history
Peripheral primer : Curiosity
Berdan primer : Type of primer
Boxer primers : Type of primer
Primer sizes : Primer technology
Electrical : Primer type

(The only picture in this section is one of the Peripheral primer (Steyr ammo) that is not representative of a typical primer today - I think that in the scope of an encyclopedia, we should go to the essential, that is, an illustration of a today's primer - in the primer article)

Black powder : Propellant technology
Nitrocellulose (single base propellants) : Propellant type
Double base propellants : Propellant type
Solid propellants (caseless ammunition) : propellant type
Load density and consistency : Propellant technology
Chamber Straight vs bottleneck : Chamber types

Static friction and ignition : Internal Ballistics
Kinetic friction : Internal Ballistics
The role of inertia : Internal Ballistics
Pressure : Internal Ballistics
Pressure vs distance traveled : Internal Ballistics
Peak vs area : Internal Ballistics
Propellant burnout : Internal Ballistics
Muzzle pressure concerns : Internal Ballistics
Bore diameter and energy transfer : Internal Ballistics
Ratio of propellant to projectile mass : Internal Ballistics
Accuracy and bore characteristics : Mix of barrel technology and Internal Ballistics
Autoloading firearms : Internal Ballistics (should be renamed "autoloading effect on energy")
Blowback firearms : Firearm technology
Gas-operated firearms : Firearm technology (plus a little of ballistic behaviour)
Recoil-operated firearms : Firearm technology

Again, I find these explanations very valuable but I think it should be reorganized a little bit.

--Mdeby (talk) 11:49, 29 December 2007 (UTC)

Well, if you're willing to do the work, I'd be for splitting the article up rather than shortening the sections. You could place a split tag to split the two sections of priming and propellant off into their own articles. I don't know if a 'propellant' article exists, but I'm pretty certain a priming one does not. We should put a merge tag for pinfire at least as that really doesn't need its own article if you've got an entire article just for primers. Seems like it cuts the article into thirds and makes logical sense.--Asams10 (talk) 15:42, 29 December 2007 (UTC)
Before you get carried away. Considering the article as a whole, and particularly the Propellant section - a number of the sections/subsections have {main} at the top of the section/subsection - which means these articles already exist. This applies to Flintlock, Caplock, Rimfire, Pinfire, Gunpowder, Smokeless powder, Ballistite, Cordite, which means the internal ballistics article only needs to summarise them; and you do not need to recreate new articles.Pyrotec (talk) 17:35, 29 December 2007 (UTC)
Don't worry, there will be no carry away !
Like Asams10, I think a split, rather a shortening, would be nice. With all existing content preserved. But before that, I propose to add first some material, it may provide new lights and we will have plenty of chances to discuss it before making any changes to the structure. It may take time on my side to come up with it, probably some time next week, not before. —Preceding unsigned comment added by Mdeby (talk • contribs) 02:09, 30 December 2007 (UTC)