BP production newbie questions

[famdoc2892]

[This will be old hat for you old hands, so let me thank you in advance for your patience and help. Thanks especially to Cal50 whose PMs have helped already. For the benefit of others, I'm reproducing my questions to him in a new thread.]

I'm making my own black willow charcoal using a cookie tin retort to process young branches under 2" diameter and stripped of their bark while green. My KNO3 is Spectracide Stump remover, and industrial supply powdered sulfur at 99.8%+ purity. Ground each ingredient in a small (1-1 1/2 cup) ceramic mortar till finely powdered, mixed at 75/13/12 by weight using my reloading powder scale and ground together, added water to clay consistency, ground a little more and screened onto butcher paper through a window screen (about 1.2 mm). May have been a bit moist, got some "strings" of granules that I put back through screen when dry, then sifted out fines through a skillet grease screen (about 0.8mm). As noted, burning a sample was disappointing. [loud hissing "smoke bomb"]

I'm in process of building a ball mill, and was undecided about the value of pressing the powder. I've read through Ulrich Bretscher's page and that by Don Williams, and much of Ian von Maltitz's book, but feeling a little discouraged about my current results. I'm wondering if the equipment is the difference? I'm an experienced reloader and caster, so not afraid of a new process and learning curve, but want to make sure I'm on the right track. Any thought? Sound familiar?

[Boz330]

There is a sticky on the ML section that can answer all of your questions. If you intend to load cartridges you will need to press your powder into pucks to get any descent velocity. The screened powder works fine in a ML if you load by weight. The limiting factor of case capacity keeps you from getting enough weight of powder into the case. I found that in a 40-65 that there was 200fps difference between screened powder and corned (puck method).
There is also a formula on that thread for your ingredients. Your formula is off a little. You will find that the ball mill will make it a lot easier. BTW you can find KNO3 at a reasonable enough price on line and there are several suppliers listed in that thread as well. I used the Spectrcide and got reasonable results but the online stuff is cheaper.
I have a picture in that thread of a puck maker that you can use in a vice. I'm getting 1200fps from a 400gr slug. The same slug with 2F Swiss yields 1275fps. The screened powder was giving me just slightly over 1000fps.
Hope this helps. You will find that there is more than one way to do it and they all work.

Bob

[Texantothecore]

Don't be discouraged, you're doing fine. It is not unusual to get something less than perfect on your first try.

The ball mill is going to be a huge help as the particles will be more uniform and probably smaller.

I would use the following standard ratios for your first successful batch:

KNO3= 15 parts
Charcoal = 3 parts
Sulfur = 2 parts

This is the standard mix, although definitely not the only one, and it should yield good, repeatable velocity.

Castboolit threads to read:

http://castboolits.gunloads.com/showthread.php?103852-My-homemade-black-powder&
Wide ranging discussion with a number of noobies as well as some real experts. This thread has 840 posts and takes a bit of time to read through but it is worth the time.


http://castboolits.gunloads.com/showthread.php?185261-DIY-bp-gurus-will-I-need-to-corn-my-black-powder-for-use-in-cartrides

This thread is much shorter and is more focused than the the above thread. Boz330 and Cal50 played a large role on this thread as well as others who are making their own. My thanks to them for their contribution. Includes part numbers and sources for cheap equipment, usually from McMaster-Carr and Harbor Freight.