Without considering the initial investment in tooling, the cost of the chemicals alone - which is really all that's required - would work out to about a few dollars for a pound of any granule size powder. That resulting powder, whether the CIA or ball milling methods are employed, would be about 20% less potent than any commercial black powder, and perfect for a muzzleloader or cap-n-ball revolver ... it would not be as good for cartridge guns. Also, unlike the faux black powders (Pyrodex et al) it will work very well with flint guns. It means upping the load in any gun. If 70 grains of commercial was used, it'll take about 85 grains of homemade to equal the commercial powder.
On the super cheap and simple side, getting a cheap Harbor Freight ball mill, about 50-100 of yer lead balls, and some screens about all the tooling actually required. The chemicals are easy to find and cheap ...
DudaDiesel.com for KNO3 ($13/5lbs) and sulfur ($5/3lbs).
FireworkCharcoal.com for willow charcoal ($15/lb)
I'm not at all cavalier about black powder. It IS an explosive. I'm Very concerned about actually making black powder from a safety perspective. One shouldn't just dive into making black powder without a cautionary fear and a dedicated responsibility to safety. If yer head's not screwed on right 'n' tight, it'd be foolish to begin the BP making process. 'Nuff said.
Weigh out the chemicals (okay, you'll need a cheap digital scale) to create no more than an 8oz weight of BP for starters. Ball mill the ingredients for 8 to 12 hours. The results are called green meal powder - put it in a bowl and add a small amount of water to make it into a dough-like substance that's moist/damp and not fully wet. Now it's inert and there's no chance of it igniting. Grate that dough ball over a 20 mesh stainless steel screen. Sift the results over a 30 mesh screen - what sits on top of the 30 mesh screen is 2F powder - grate that over a 30 mesh screen then sift that on top of a 40 mesh screen. What sits on top of the 40 mesh screen is 3F powder. Allow the powder to thoroughly dry - spreading it out on foil or paper in the sun will take only an hour or so if the relative humidity is low. That's about it. Not too complicated, eh? And relatively safe.
Binder. Some folks do the above BP making method, but most will add about a 1-2% binder to the initial mix that goes into the ball mill. A binder does just that - makes the KNO3 infuse better into the resulting black powder. Dextrin is the commonly used binder, which is essentially corn starch. Dextrin is about $4/lb and will last for many pounds of black powder making.
However, if the resulting dampened powder is to be "corned", no binder is required because the corning process requires compressing the powder into "pucks" and that process will plasticize the sulfur and thus bind all 3 three ingredients. Corning will create black powder that is quite suitable for cartridge building. It is NOT a requirement for muzzleloaders.
The basic black powder formula is 75% oxygen (KNO3 - potassium nitrate), 15% fuel (charcoal), 10% igniter (sulfur).
A small 1/2lb batch (8oz weight) would require (by weight) 6ozs KNO3, 1.2ozs charcoal, .8ozs sulfur, .16ozs dextrin. Put all 4 ingredients in a ball mill, add in 50 to 100 lead balls, mill that for 8-12 hours. How safe is the milling process? The HF ball mill drum is rubber lined. The grinders are non-sparking lead balls. It takes significant heat to ignite black powder. Just ain't gonna happen in that ball mill.
To be safe, my milling will be done outside and 100ft from my house, and inside a small shed. Better to be safe than sorry. There are hundreds if not thousands of folks ball milling black powder, most are doing it for pyrotechnics and not muzzleloaders. Haven't heard of a ball mill blowing up, yet.
The reason why there are BP making explosions is almost always by lighting up the resulting air float BP particles that becomes a fuse that travels back to the actual powder store itself. Opening up a ball mill drum will have air float dust coming out like the smoke that it is. It's not a difficult task to minimize the air float. Once transported to a bowl for adding in water, the powder is rendered inert - wet powder will have a hard time to ignite with a flame let alone a spark of heat. Grating the damp powder over stainless steel screens won't ignite it. After the granules have been left to dry, now it's essentially the same as the commercial powder you've got in yer powder cans, yer powder horns, yer powder pan chargers, yer guns - no different, and no more dangerous or safer.
Well, almost the same as commercial black powder. Almost all of the commercial BP will add a coating of graphite to the powder granules as a separate step. After the black powder has been made and sized (grated and screened), a small amount of graphite is added to the powder, and is milled without grinders for 2 hours. This coats the granules with the graphite and is s'posed to make it less prone to absorbing water. This will also somewhat lessen its ability to ignite.
Hope the above helps a bit.
