DIY bp gurus: will I need to corn my black powder? for use in cartrides?

[Texantothecore]

I was wondering what the effect would be if I did not corn my homemade bp that is to be used in .45-70 cartridges. I will be using dextrin in the mix.

Any insights will be quite welcome.

[John Boy]

I was wondering what the effect would be if I did not corn my homemade bp

I don't have a clue - try it and see if the SD's over the chronograph are erratic or not. Presume your not also going to polish the polish the powder

[Texantothecore]

I don't have a clue - try it and see if the SD's over the chronograph are erratic or not. Presume your not also going to polish the polish the powder

Polish the powder? I have not heard of that before. The only polisher I have is an old Sunbeam floor polisher and I don't think would work on a kernel of powder. Potentially very messy. Lol!

[Nobade]

When I tried that it shot accurately enough but wasn't very powerful. IIRC I could only fit about 45 grains of powder in the case. After I started pressing it, a full 70 grains fits and it's way more powerful.

What was funny was the 44spl revolver and screened powder. 400 fps was all it could muster, easy shooting but really slow! BTW, the pressed powder does 850 fps.

-Nobade

[John Boy]

Potentially very messy. Lol!

Not at all messy. Mix the powder with 6% water and tumbler dry down to 1.5 to 2% over a 24 hr period. Polishing froms a glaze and compacts the insides of the grains and is a standard step in the making of 'sporting gunpowder'. Without the process, ones just ends up with muzzle gunpowder with a low density.
So if you are not concerned with the SD spread of your powder and haven't really read up on on the standard processes making gunpowder - do what you want to do and see how it shoots. Good Luck!

[Boz330]

What Nobade said. I add a little graphite to the corned powder so it will go through a powder measure smoother.
In a 40-65, screened powder gives me 1000+FPS for a 400gr boolit. With the corned powder I get 1200+FPS for the same boolit. Swiss gives me 1275FPS.
Nobade is getting his powder much denser than I am and the power comes from the weight. I did a test in a ML using screened, corned, and Kik, measured by weight and the velocities were within 50FPS of each other with the home made giving the higher velocities. But the volumes were considerably higher as were the ESs. But to answer your question you will need to corn it to get the density for a cartridge.

Bob

[Texantothecore]

Not at all messy. Mix the powder with 6% water and tumbler dry down to 1.5 to 2% over a 24 hr period. Polishing froms a glaze and compacts the insides of the grains and is a standard step in the making of 'sporting gunpowder'. Without the process, ones just ends up with muzzle gunpowder with a low density.
So if you are not concerned with the SD spread of your powder and haven't really read up on on the standard processes making gunpowder - do what you want to do and see how it shoots. Good Luck!

John,

What kind of tumbler are you using to dry down your powder?

Are you simply putting in the screened powder into the tumbler or are you drying it down into a puck and shattering the puck to get the correct size kernels and then tumbling?

I do not have an area in which to use a tumbler, just my office at home so my equipment is kept simple and easy to store in a chest.

I am sort of thinking that I will have a brass or bronze cartridge collar machined that will hold an extra 25 or thirty grains of BP and then using a dowel or possibly one of the dies that are designed to compress BP to get more screened powder into the cartridge with one compression stroke as I have read on this forum that compressing smaller incremental amounts doesn't work very well. High SDs.

What do you mean by ESs?

[Boz330]

ESs are extreme spreads. I had no luck at all with incremental compression.

Bob

[cal50]

Dextrin is a binder used in pyrotechnic black powder / star comps. It adds nothing positive for rifle propellant and will slow down the burn rate. You really want / need to press your powder in a die to obtain a good density before corning. Polishing the powder is simply tumbling the loose grained powder. You can add graphite and it will give it a nice color and makes the powder flow nice.

[cal50]

Compressing your powder in a press die gives it the density for good BP. Corning it only produces the various grain sizes.

[cal50]

Here is a good read on the topic :

http://www.gunthorp.com/Mfg%20Black%20Pdr.htm

[Texantothecore]

Here is a good read on the topic :

http://www.gunthorp.com/Mfg%20Black%20Pdr.htm

I just read that link and it is very good, the best I have ever seen. The simplicity of the equipment is quite impressive, to say the least. I will be probably be building a press in the very near future. Thanks.

Do you approximately how much pressure would be required to press a one pound batch to 1.7 Grams per CC? From the description it doesn't sound as if it is much.

For those of you following along and thinking about making your own, the link is a must read.

[cal50]

You would not press 1lb at a time. I press about a cup or more at a time into my die. I have a harbor freight press and I put a pressure gage on the hydraulic jack. I press the powder and keep adding pressure until it holds steady on my gage for 20 minutes. Once the pressed powder comes out of the die it sounds like china if tapped. I use a 3" diameter die and the powder "puck" is around 5/8" thick. I wait until dry to corn it.

I just read that link and it is very good, the best I have ever seen. The simplicity of the equipment is quite impressive, to say the least. I will be probably be building a press in the very near future. Thanks.

Do you approximately how much pressure would be required to press a one pound batch to 1.7 Grams per CC? From the description it doesn't sound as if it is much.

For those of you following along and thinking about making your own, the link is a must read.

[cal50]

I did the math for my ram size & die so my pressure will vary from other set ups.
If you have a graduated cylinder just put 10 or 20 CC'c of powder in the cylinder then weigh it to get an idea of density or grams / cc.

I can say my powder performs better than Goex but that has a lot to do with milling, sulfur content, quality of charcoal and my process.

[Texantothecore]

You would not press 1lb at a time. I press about a cup or more at a time into my die. I have a harbor freight press and I put a pressure gage on the hydraulic jack. I press the powder and keep adding pressure until it holds steady on my gage for 20 minutes. Once the pressed powder comes out of the die it sounds like china if tapped. I use a 3" diameter die and the powder "puck" is around 5/8" thick. I wait until dry to corn it.

I would think that the Harbor Freight 1/2 ton arbor press would do just fine in this application. I will look at one tonight.

[cal50]

You really want a press that holds pressure. A screw type or hydraulic with a gage is even better. You will be amazed at how much powder compresses down and it takes several more pumps on the jack to get it to settle down.

[Texantothecore]

You really want a press that holds pressure. A screw type or hydraulic with a gage is even better. You will be amazed at how much powder compresses down and it takes several more pumps on the jack to get it to settle down.

I had thought that a screw press might work pretty well and i will price the parts this weekend.
The other idea that immediately came to minid was making use of a 2 ton shop jack which will hold up an F150 pretty reliably. I am sort of spinning one around in my mind, upside down, sideways and right side up.

[Boz330]

My screw type press. Not sophisticated but works for what I'm doing. After a very short time you can tighten it more.

Bob

[Texantothecore]

That vise occurred to me too. I'll bet that works like a charm. I may look for one at one of our shops that specialises in (mostly worn out) tools and I'll bet I can find one that is suitable. Thank you for that pic as it is really valuable to see the simplicity with which you have accomplished the task at hand.

[John Boy]

What kind of tumbler are you using to dry down your powder?

For starters, I haven't made 'fire cracker' powder since the age of 10 or 11. What I posted to you is what the major black powder manufacturers do and if not done - the results. Would stand to reason - if one runs with the big boys - ones powder can't be all that bad ... but not equal to!