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Author: Subject: Gun Propellants: Single, Double and Tripple based
Hennig Brand
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[*] posted on 10-10-2014 at 08:33


The extrusion idea is not a bad one and it is how it is done commercially IIRC. I was thinking of some kind of rotary cutter with rollers for feeding the sheets into the cutter powered by a hand crank (or motor). The cutting wheel/roller could have little cutters that would take little bites of the required size out of the sheet as it was fed in. The grains would fall into a collection bin.

I am familiar with the ballistic pendulum. I actually just bought a Shooting Chrony a month or two ago, and have tested the muzzle velocity of just about every gun and load within reach since then. :D


[Edited on 10-10-2014 by Hennig Brand]




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[*] posted on 10-10-2014 at 09:29




Pasta maker-

The roller part of the machine also works quite well for processing plastic explosive materials, rather easier than rolling a wine bottle over a sheet of plastique for hours on end.




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[*] posted on 10-10-2014 at 10:41


Shotguns use the fastest burning powers so you are relatively safe performing this type of experiment with a shotgun. Rifles use slow burning powder so if your home made powder burns faster than the original you will blow up your rifle.


There are computer programs like Quickload which simulate the combustion of powder in the chamber, the pressure generated and calculate the acceleration of the bullet. It becomes quite complicated since the burn rate is proportional to the pressure in the chamber and many other factors like the grain size.

Powder makers do things like adding graphite to the power to block the penetration of infrared radiation which slows the heating of the grains and the burning process. It becomes very complicated.

I wanted to convert my cap and ball black powder revolver to smokeless powder so I calculated the correct load. The original was about 25 grains of black powder, the calculated load was 6 grains of smokeless powder suitable for a 9mm handgun. I needed to keep the pressure below 10,000PSI since it is what the gun is designed for. Modern guns use much higher pressures. The ability to use smokeless would be nice since is does not leave residue that makes it hard to clean the gun.

However I found that the cap could not ignite the smokeless powder
(even though it pushed the bullet 1/2 way down the barrel). So I added a small piece of magicians flash paper (nitro cellulose). The gun would now fire (weakly) but there was still a bunch of unburned powder left in the
barrel. The large chamber volume and low sectional density of the
spherical bullet work to keep the pressure low, apparently too low to burn
this particular smokeless powder. Maybe a faster powder intended for a
shotgun would work.

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[*] posted on 10-10-2014 at 15:40


By controlling the viscosity of the NC lacquer, by adjusting the amount of solvent used, it can be made to form the correct thickness by simply pouring it out onto a flat surface. Nice pasta maker; I imagine it could definitely be made to work. The grain size of the commercial propellant which came out of the 410 shell was really very small. I have never made more than about a quarter pound of plastic explosive at a time, so the amount of kneading was minimal (15 minutes maybe), but for larger amounts some decent equipment would definitely be a huge labor saver.

The same smokeless propellants that are used in shotguns are very often used in handguns as well, from what I have seen. The single base propellant that I made has relatively large average particle size, so I would imagine it would be safe to test in a rifle. Modern rifles are also normally extremely overbuilt in terms of their ability to withstand pressure. I really don't think that what I am doing is all that dangerous. Once the NC is no longer in the fibrous form, and given the correct load, it really is very safe material to fire in a gun. This extreme improvement in safety was what was so revolutionary about Poudre B; that coupled with the much greater performance and almost no smoke production as compared to black powder. It would be a good idea to examine the grain size of typical commercial rifle powder, specified for the particular rifle used, and also to start with lighter loads when testing homemade propellant however.

I don't think I would want to go anywhere near the maximum pressure that a gun could withstand. Black powder guns, especially the older ones, were usually made of much lower strength materials than the modern smokeless propellant types. Being out here in the country, I would tend to test my powder by simply seeing how it performs in a gun. The percussion caps made for black powder guns are much weaker than the caps made for modern smokeless propellants. I thought the reason for the graphite coating on propellant grains was to prevent static electricity sparks from igniting the propellant.


[Edited on 11-10-2014 by Hennig Brand]




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[*] posted on 19-10-2014 at 08:26


Another batch of single base propellant was made from the same batch of homemade nitrocellulose. The propellant was cut up finer this time and loaded into 410 shells. One shell had the original #4 lead shot and the other was loaded with copper coated BBs. One gram of powder was used in each shell. The results were counterintuitive; there seemed to be less penetration even though the powder was finer. The balls were only just embedded in the target.

Double Base Propellant.jpg - 431kB Projectiles for Single Base Test.jpg - 469kB Homemade Single Base Test.jpg - 465kB


Next, a batch of nitrocellulose with a low level of nitration that was made two years ago was used to make a double base propellant. The nitrocellulose was dissolved in acetone and then nitroglycerine was added. The composition of the propellant was 60% NC and 40% NG. Even though the nitrocellulose was much weaker than the nitrocellulose used for the single base propellant, the double base propellant was very powerful. A one gram load of the homemade propellant seems to have produced similar results as the commercial load when fired at the 3/4" plywood target.

The upper hole, in the following pictures, is from the earlier test with the original powder load (1g of commercial double base powder). The lower hole is from the later test using 1g of homemade double base. The factory load of #4 lead shot was used in both tests.


Homemade Double Base Smokeless Propellant.jpg - 392kB Homemade Double Base Test Front View.jpg - 446kB Homemade Double Base Test Rear View.jpg - 440kB

The single base propellant should have performed much better, I think. It is obviously much more difficult to synthesis nitrocellulose with a high level of nitration than it is to synthesis nitroglycerine. It is also much easier to neutralize residual acidity from NG than it is from NC. NG can be made with much greater acid economy as well, especially if the spent acids are not recycled. I definitely see some of the advantages of double base propellants already.


[Edited on 19-10-2014 by Hennig Brand]




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[*] posted on 22-10-2014 at 11:12


The attached tables were taken from the text, “Chemical Analysis of Firearms, Ammunition, and Gunshot Residue” by James Smyth Wallace. The tables list the formulas for many common single base and double base smokeless propellants, which I thought would be very useful to someone making their own propellants. The chapter before the one on propellants is on primers, which is also very interesting. Many primer compositions are listed, often with a bit of description including history of use. The text can be found online.



Attachment: Single and Double Base Propellant Composition Tables.pdf (243kB)
This file has been downloaded 499 times





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[*] posted on 25-10-2014 at 09:44


A test was just performed using a single shot .22 cal. rifle and .22LR rounds with 40 grain bullets. The 0.1g of commercial double base propellant was removed from one of the rounds and replaced with 0.1g of the homemade double base smokeless propellant. The homemade propellant was screened using a small kitchen sieve to get reasonably fine grains (the commercial stuff was very fine). The homemade propellant outperformed the commercial propellant by a significant amount. The factory load gave a muzzle velocity of 1220 fps, while the homemade propellant produced a muzzle velocity of 1329 fps. Muzzle velocities were measured with a ballistic chronograph.


Sizing Double Base Propellant.jpg - 241kB

Commercial Double Base .22LR.jpg - 467kB Homemade Double Base .22LR.jpg - 462kB


Here is the result of a test using a round which was hot-loaded with the homemade double base. Instead of 0.1g, 0.11g was used. The muzzle velocity of the bullet was measured as 1437 fps. Now we are really zinging. I don't think I will try and cram any more powder into the tiny .22 cal. cartridge, though I am sure I could bring the muzzle velocity up to 1600 fps if I really wanted to.

Homemade Double Base Hotload .22LR.jpg - 500kB


I have included a picture that I meant to post earlier showing the rolling cutter and propellant on a cutting board. The propellant on the board is homemade single base from earlier tests. The double base propellant, when still slightly damp with acetone, can be cut up very quickly (few minutes) when done in small quantities at a time (6-10g for example).

Single Base Propellant Cut Up With Rolling Cutter.jpg - 374kB


[Edited on 26-10-2014 by Hennig Brand]




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[*] posted on 26-10-2014 at 11:38


That's impressive. Why does your propellant perform better than the commercial one? Is it the grain size, or the fact that yours doesn't have other additives that dilute it?
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[*] posted on 26-10-2014 at 15:55


Thanks, particle size and lack of diluents could both be factors. Changing particle size, even while keeping everything else the same, can have a big impact on muzzle velocity. I think most samples of nitroglycerin tend to be fairly pure, however, there can be a lot of variation in the level of nitration or strength from sample to sample with nitrocellulose. The same simple separation and purification processes that exist for nitroglycerin are not possible with nitrocellulose. Nitrocellulose also normally makes up the largest proportion by weight of smokeless propellants (60% in my case). A higher proportion of nitroglycerin would normally make a smokeless propellant more powerful as well. It is very possible that the commercial propellant has less than 40% nitroglycerin.

Some of the additives/diluents, like a good stabilizer, are very important if the propellant is going to be stored for any length of time; especially if it will be stored in any quantity.




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[*] posted on 26-10-2014 at 16:09


Have you tried nitration of microcrystalline cellulose to produce a single base NC powder that is usable without subsequent granulation? This might also provide a good starting material for double based ball powder of very fine mesh size.
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[*] posted on 27-10-2014 at 04:17


I haven't tried it, but it does sound like a possible way to get useful grain size without the need for granulation post reaction. It could be hard to properly incorporate the stabilizer if the nitrocellulose isn't colloided and the stabilizer isn't dissolved in the solvent though. I have never made microcrystalline cellulose, but I am interested in it. I remember seeing the thread(s) with what looked like fairly simple processes for producing MCC for the hobbyist.



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[*] posted on 28-10-2014 at 00:17


Smokeless rocket propellant :

DEGDN : 45 %
NC /12,5%/ : 53 %


Clipboard01.jpg - 427kB 023.JPG - 2.6MB 030.JPG - 2.7MB

[Edited on 28-10-2014 by specialactivitieSK]
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[*] posted on 5-11-2014 at 10:19
Estimation of Percentage Nitrogen


Some more cotton was nitrated.

Materials:
9.8g Cotton Balls (oven dried for 60 minutes at 110C)
100g NH4NO3 (oven dried fertilizer grade)
180mL H2SO4 (91% drain cleaner)

Cotton was allowed to nitrate in the mixed acid for about 48 hours in a lightly sealed vessel at room temperature and in the dark. Post nitration, the product was well washed and allowed to soak in dilute sodium bicarbonate solution for 48 hours before being well rinsed with clean water again.

Yield:
15.96g (dried at room temperature until weight ceased to decrease)

According to the text "Military Explosives", cotton oven dried at 110C would have a moisture content of about 0.5wt%. Cotton which is not oven dried can easily contain 5-7% moisture content. Using the table in the following patent the moisture content of the air dried, at room temperature, nitrocellulose should be approximately 2-2.5wt%.

Attachment: Patent With Nitrocellulose Moisture Contents US2312741.pdf (275kB)
This file has been downloaded 299 times

Compared to using a nitrometer the following method of determining percentage nitrogen is fairly crude, however it is a simple method to implement and it should provide a useful approximation.

Theoretical maximum percentage nitrogen 14.14%; C6H7(NO2)3O5 is the formula for the monomer.

Nitrocellulose trinitrate monomer MW: 297 g/mol
Cellulose monomer MW: 162 g/mol
Assume oven dried cellulose had 0.5wt% water content.
Assume ambient air dried nitrocellulose had 2wt% water content.
Assume that other than water the cotton feed and nitrocellulose product had no impurities.
Assume no losses due to oxidation or loose fibers poured out during washing.

Approximation of Percentage Nitrogen:

Theoretical Yield
0.995 * (9.8g / 162g/mol) * 297g/mol = 17.88g

Percentage Nitrogen
0.98 * (15.96g / 17.88g) * 14.14%N = 12.37%N


About 16g of Fibrous Nitrocellulose.jpg - 390kB


Found the following pdf online, which I thought might be useful. It is a brief overview of a nitrocellulose manufacturing process.

Attachment: Nitrocellulose Manufacturing Process.pdf (64kB)
This file has been downloaded 510 times


[Edited on 6-11-2014 by Hennig Brand]




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[*] posted on 8-11-2014 at 05:11


This should have been included in the last post, but I didn't think to do it at the time.

A simple burn test was performed using less than a gram of the above nitrocellulose product loosely balled up. It burned extremely fast with a huge whump sound and made a very large fireball which burned all of the hair off the fingers of the hand holding the wooden match. I was a little surprised at how fast it burned given that the percent nitrogen was estimated to be only about 12.4%. I suppose 12.4% is not really very far from 13% though. From what I have seen nitrocellulose with this level of nitration makes perfectly serviceable smokeless propellant, especially if used in a double base formulation with nitroglycerine.




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[*] posted on 10-11-2014 at 16:04


Hennig Brand, I am thoroughly interested in this thread and am amazed what you have achieved so far. I really never thought smokeless powder comparable to factory could be made at home. Closest I have got to gun propellant is black powder lol.

One thing I wanted to mention, if you wanted to try using microcrystalline cellulose and don't mind the trouble, you can extract it from certain brands of ASA that only contain that one additive. I currently have about four ounces of it from making picric acid. Just a thought. Keep up the great work, I am extremely interested.

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[*] posted on 11-11-2014 at 02:31


Microcrystalline cellulose is extremely easy to make yourself. Just hydrolyse cotton wool with dilute hydrochloric acid (IIRC 10 % HCl was best). It takes a couple of hours at ca. 90 C, and then you just filter and wash the product.
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[*] posted on 11-11-2014 at 04:30


I suppose microcrystalline cellulose would likely be easier to nitrate than a big fluffy piece of cotton. Mixing should be much easier for one.

Just found the following in the "Tri-Nitrocellulose" thread. I believe I read this thread several years ago and just forgot about it.

Quote: Originally posted by Rosco Bodine  
Microcrystalline cellulose should be easily nitratable , but I have never seen it described . IIRC , cellulose flour is what is the name for it as a food additive and it is soluble like starch , but has a small number like 8 cellulose units which has a crystalline form . There are small bottles sold as a dietary supplement ,
" soluble fiber " type of material for an inflated price . But the same material is sold cheaply in bulk as a thickener additive for foods , similar to rice and potato flour .


Quote: Originally posted by ordenblitz  
Roscoe,

You are correct that microcrystalline cellulose is easy to nitrate, much easier in fact since it is more dense that cotton and you can get more in the mixed acids. You can stir it more effectively and it nitrates faster since the small crystals are better exposed to the acid. After nitration is complete, leaving it to stand causes the MCNC to float to the surface of the acid in a dense layer that can be pulled out of a beaker in virtually one chunk. This brings along less spent acid and allows faster quenching thus keeping the N content as high as possible. Stabilization is a breeze as well since MCC does not have the tubular cellulose structure that cotton has therefore it traps less sulfuric acid esters. A short boil is all that's needed. The best thing about MCNC is that it retains the physical characteristics of MCC. It compresses very well in a hard and durable plastic form. Tabletted material looks very much like ivory.

I know a little bit about this since a while back, I applied for a patent on MCNC. They are slow at the USPTO it's not even in the pending list yet. My last patent took 1.5 years to show up on the website after filing.



[Edited on 12-11-2014 by Hennig Brand]




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[*] posted on 13-11-2014 at 09:55
Estimation of Percentage Nitrogen Correction


I made a mistake in the above percentage nitrogen estimation. There was a week between when I performed the post reaction workup and when I actually did the reporting. I simply forgot, and forgot to write down, that I didn't add the last couple pieces of cotton that were weighed out so the amount of cotton nitrated was slightly less than reported. The method itself is still correct. Another experiment was just conducted where 4.99g of the same oven dried cotton was nitrated in the same way but for only 35 hours (which I believe is still a long time past the point of diminishing returns so to speak). A room temperature, air dried, yield of 8.52g was obtained which corresponds to 12.97%N estimated using the calculation from the first post. I also found some rough notes for several other nitrocellulose syntheses that were conducted over the past few years, using essentially the same grade of ammonium nitrate and the same concentration of sulfuric acid, and yields corresponded to percentage nitrogen values between 12.8 and 13.05%N in all cases. In those earlier nitrations the cotton was not oven dried, so the cotton was assumed to contain 5% water instead of 0.5% (assumed value for the oven dried cotton).

I also noticed that using significantly less nitration time, less sulfuric acid and ammonium nitrate, than what was used in the above example, still produced about the same level of nitration. I believe I switched to using larger amounts of sulfuric acid and ammonium nitrate because it made the process easier and also because it was felt that the level of nitration might be higher. I believed that extra time, especially when using a nitrate salt instead of HNO3, would increase the level of nitration (this is true up to a point). Here is a link to a couple of yields reported back in 2011 by me in another nitrocellulose thread.

http://www.sciencemadness.org/talk/viewthread.php?tid=13957#...

I knew that percentage nitrogen value seemed awfully low. :) Sorry about that.


[Edited on 13-11-2014 by Hennig Brand]




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[*] posted on 13-11-2014 at 10:39


The microcrystalline nitrocellulose would seem to be promising for making extremely fast small mesh powders for small caliber pistol or small caliber rimfire loadings which may be able to tolerate hotter loadings that could damage larger caliber arms. This might even be a niche application for PETN based or hybrid double or triple base mixture powders as a way of increasing energy for small caliber loadings using hot loads that would not be tolerated in larger caliber arms. There has been commercial development of hotter and hotter powders for rimfire .22 and .22 magnum and there is an even smaller BB or .17 caliber rimfire.
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[*] posted on 13-11-2014 at 11:35


Assuming that a stabilizer such as diphenylamine needs to be added to a microcrystalline nitrocellulose powder; do you think that simply washing the powder with a solution of the stabilizer might be acceptable?



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[*] posted on 13-11-2014 at 11:51


What are the long term storage stability characteristics for microcrystalline nitrocellulose I don't know. It may be easier to stabilize it since it already has higher purity from synthesis and less inherent instability caused by impurities or occluded acidity. So something like a betaine or cyanoguanidine solution soak and drying may be sufficient stabilization if stabilization is even needed. Testing is really the only way to find out what is needed and what works.
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[*] posted on 14-11-2014 at 03:04


Wow, what a great thread! Here is a link to the "Tri-Nitrocellulose" thread, where the couple quotes above were taken from, and where microcrystalline nitrocellulose is discussed in depth.

http://www.sciencemadness.org/talk/viewthread.php?tid=1007&p...




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[*] posted on 15-11-2014 at 05:54


I don't know how one can get completely rid of the H2SO4 in the NC. I wonder if NC can be made with HNO3 only(with less yields then RDX or PETN). Such cotton I guess will be very easy to purify and stabilize. Do you think such cotton can be used instead of lead styphnate, as a kick starter in fuse cannons or as last option for blast cap base charge(I'd say the power is between AP and TNP)?
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[*] posted on 15-11-2014 at 07:20


sulfoester free nitrocellulose is possible

see this linked post for a patent US2776965
for the manufacture of sulfoester free nitrocellulose , where no sulfuric acid at all is present in the nitration mixture , but magnesium nitrate is used in the place of sulfuric acid as a substitute dehydrating agent.

http://www.sciencemadness.org/talk/viewthread.php?tid=4701&g...
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[*] posted on 15-11-2014 at 08:09


According to COPAE and other sources it is impossible to completely remove residual acidy, and other contaminants produced during the nitration, from nitrocellulose without additional special techniques that go way beyond simple washing. This is true at least for traditional nitration methods. Nitrocellulose fibers are tubular in structure which act like little capillaries locking in residual acidy and preventing its removal by simple washing and neutralization techniques. COPAE describes mechanical methods which process the nitrocellulose in such away so as to open up the fibers exposing the interior more which then allows the removal of the impurities by washing and boiling processes. The text, "Military Explosives", describes a poaching process where the nitrocellulose is boiled in a dilute sodium carbonate solution (2% solution IIRC), which as well as removing acidity is supposed to break down and remove other impurities produced during the nitration (other esters, etc), which would otherwise lower stability. I have kept several samples of highly nitrated cellulose in small quantities for a couple years or more and have always noticed that it is significantly degraded in a matter of months even though it was extremely well washed and the residual acidity (at least on the exterior of the fibers) was neutralized.

One very nice property of microcrystalline nitrocellulose is that it apparently does not have the tubular structure and so is very easy to wash and stabilize. This is discussed in the thread I just linked to in the last post.

I don't know how well nitrocellulose would work as a base charge, but the microcrystalline nitrocellulose type would likely have the best chance of performing well. From reading "Military Explosives", it seems that nitrocellulose can be at least as powerful as TNT when used as a detonating explosive. Not entirely sure how even MCNN would perform in the small diameter of a blasting cap though. I may give it a try. The percentage nitrogen and purity of RDX, PETN and NG, for instance, can be easily increased to very near the theoretical maximum by very simple washing and recrystallization techniques which remove lower nitrates and other impurities. These simple purification processes are not possible with nitrocellulose mostly because it is a polymer from what I understand. This makes production of high nitration level and high purity nitrocellulose relatively labor intensive/difficult and expensive. Nitrocellulose makes fantastic propellants though.




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