Powder burns better and cleaner, the higher the pressure it reaches. A good crimp and a good compressed load should give the best results.
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Potassium Perchlorate maybe?
How about:
10% Potassium Perchlorate
50% Potassium Nitrate
30% Ascorbic Acid
5% Manganese Dioxide
5% charcoal
Its possible that varying these amounts by 1-2% may improve performance even more but if this works out to be the equivalent of 777 I'll have my final formula. Nice round percentage numbers for making small amounts of it.
Potassium Perchlorate is used a lot in fireworks as it does oxidize better than potassium Nitrate, and it IS one of the components of Pyrodex, but I have no experience with it.
Yes, perchlorate is a great oxidant. In this formula, I would not use manganese dioxide. Or at least I would test very carefully when using it as it can make the powder sensitive. In these substitutes I always tried to leave out the charcoal, so that the powder was as clean as possible. But coal is free, so it makes the powder economical, just how you like it...(me too).
I found the MSDS for Manganese Dioxide and it specifically says do not grind it in the presence of an Oxidizer, so this is cook method only. I suppose you could tumble it without media and it would be OK.
I think I have achieved the cheapest possible powder at this point and am now looking for the best I can make, even if that limits it to cartridges as the pressure is too high for normal BP guns
I still recommend testing its formula without manganese dioxide. Using perchlorate, I find it unnecessary to use a catalyst. If you do any tests using dioxide, do it with caution, in small doses. And please keep us informed of your results!
I got the manganese Dioxide from Amazon actually. Same Amazon that won't send me a slingshot as it is too dangerous. It was more of a bother getting the Perchlorate. HamGunner came up with this:
Golden (60%-40% Potassium Nitrate-Ascorbic Acid) had Very Good accuracy, even though it had a wide spread in velocity and slow velocity at that. I am not sure what to make of it just yet. Golden is much lighter than any of the others and the 22 gr. completely filled the chambers of my revolver cylinder, so that is why I used 22 gr. for these tests. Golden compacts into a fairly solid chunk when compressed, but seems to burn very clean. It has much less smoke than any of the others tested.
Crimson 64.3% Potassium Nitrate,32.1% Ascorbic Acid,1.8% Iron Oxide, and 1.8% charcoal) although faster than Golden, was also a bit slow with a fair amount of velocity spread, but was somewhat less bulky than Golden. It was also clean burning and gave what I will call just Good accuracy.
My Gray 61% Potassium Nitrate,31% Ascorbic Acid, 5% Manganese Dioxide, and 3% charcoal was faster yet with less velocity spread. It was clean burning and also gave just Good accuracy
Golden delivered an average of 515 fps., ES 187 fps., and SD 65 fps. Accuracy Very Good. All in a decent group with no flyers. 2 1/2" group.
Crimson delivered an average 772 fps, ES 106, and SD 43 fps. Accuracy 4" group.
Gray delivered an average 851 fps., ES 83 fps., and SD 31 fps. Accuracy 3 1/2" group..
This motivated me to focus on the "gray" composition. I was going to make some of that up today but its raining.
These tests were all 22 grains in a revolver, I'm guessing a .36, so when I load it in .38 special cases it should perform about the same. And I should be able to get 26 grains or more into a .357 case, at which point I will be satisfied.
I did buy the Potassium Perchlorate so I may go with
11% Potassium Perchlorate, 50% Potassium Nitrate,31% Ascorbic Acid, 5% Manganese Dioxide, and 3% charcoal
This is getting interesting. If we're not careful we may end up reinventing Pyrodex.
"My Gray 61% Potassium Nitrate,31% Ascorbic Acid, 5% Manganese Dioxide, and 3% charcoal was faster yet with less velocity spread. It was clean burning and also gave just Good accuracy."
While I milled and corned this mixture without any problems at all, I am not sure about doing the same with the added Potassium Perchlorate. Might not be a problem either, but I think I remember 2TM101 reading somewhere about cautions with mixtures of oxidizers and Manganese Dioxide. I am certainly not a Chemist, so the more study, the better I am guessing.
I read about the "Pyrolusite". Interesting. It has been used as far back as the Neanderthals for possibly coloring as well as enhancements to making fire.
Edit: Ok, it was right up above a few days ago.
Per 2TM101 "I found the MSDS for Manganese Dioxide and it specifically says do not grind it in the presence of an Oxidizer, so this is cook method only. I suppose you could tumble it without media and it would be OK."
If you allow me, can I give you a composition suggestion? I would use 10% perchlorate, 50% nitrate, 35% ascorbic acid, 2% manganese dioxide and 3% charcoal. I increased the fuel a little, because with the addition of perchlorate (oxygen) I think there would be a lack of fuel. But obviously everything would need testing to confirm the best composition.
60% of Pyrodex IS black powder
45% potassium nitrate
19% potassium perchlorate
11% sodium benzoate
9% charcoal
6% sulfur
6% dicyandiamide
4% dextrin
1% water
It has 40% of other stuff added just to get the DOT to classify it differently - and not work as well. I own some Pyrodex I bought when I was just starting out and its what I could get delivered to me. I won't get any more.
I'll go with this.
For one pound of powder
Perchlorate = $0.90
Nitrate = $1.25
Ascorbic Acid=$1.85
Manganese = $0.47 (at $24 a pound I'm glad its the 2% part)
Charcoal = $0.15
So about $4.52 a pound, and no hazmat fees. Figure $5 with shipping cost added in.
So for the cost of that crappy burger lunch I just had I could have 3 Lbs of powder instead, that perfectly adequate for any loading I do.
Also note that this is Potassium PERchlorate, not Potassium Chlorate. Apparently that isn't very stable.
Specifically it says powdered Magnesium - so the Manganese Dioxide may behave differently. Also if the perchlorate and MNO3 is diluted to where it is only 1/8 of the total mixture it is probably too low a concentration for it to be dangerous. I'll have to be more careful that the people who tried it the first time so I don't wind up like Berthollet here.
Interesting details about Berthollet's accident -
https://www.chemistryviews.org/chlor...ations-part-2/
His formula included 75% potassium chlorate with 10% sulfur? Mixing potassium chlorate with sulfur is risky business, best done in very small quantities (eg, making primer compound).
Since your objective is propellants, not primers, the less reactive perchlorate should be a safer alternative.
Perchlorate is much more stable than chlorate. Chlorate and sulfur is an explosive combination... only useful in primers. There are videos on YouTube showing the difference in stability between chlorate and perchlorate.
$5/lb using 22 gr works out to a powder of cost of $15.71 for 1000 rounds. I do not know how long it takes to make 3 lbs but your numbers indicate a batch size of 1 lb. Say an hour????
Cost of HP38 delivered from Powder Valley (it is in stock) is $655 for two jugs. 3.2 gr of HP38 will match or exceed your results. Powder cost for 1000 rounds works out to $18.72.
A savings of $1/hr. for an inferior product.
The risks and effort do not make sense. Smokeless powder can be stored for decades without degradation.
I understand the benefits of having something if commercial powder becomes scarce, but doing this to save money does not pencil out.