Author Topic: pressure difference in powders  (Read 9154 times)

Offline hortonstn

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pressure difference in powders
« on: July 08, 2016, 03:43:45 PM »
at the present time i shoot 80 gr fff thru my 45 with good results ive been using goex and schutzen powders im wanting to try swiss should i use
less powder ive heard it is hotter than the others?
paul

Offline smylee grouch

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Re: pressure difference in powders
« Reply #1 on: July 08, 2016, 04:23:12 PM »
I use swiss and went down in charge weight 15% from my goex load charge weight, ending up with the same velocity. I was told that swiss is a compressed powder so when you load by volume you get more weight per charge.

Offline Don Steele

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Re: pressure difference in powders
« Reply #2 on: July 08, 2016, 08:53:01 PM »
When I went from Goex to Swiss, using the same charge volume resulted in a new P.O.I. that was higher than I wanted so I cut the volume back on my measure by 5 grains. (on the powder measures scale)
Reading this thread got me to wondering and since I happen to have both Swiss 2f and Goex 2f on hand at the moment I thought I'd run a little comparison.
I'm using a plastic Thompson Center powder measure with a pouring spout that slides over the end of the powder chamber. I have checked it against weighed charges in the past and found that it's right on the money with Goex 3f. For this test, I set it to throw "80 grains" and poured it full in the same manner I do when I'm loading at the range.
For this test, I then emptied the measure into my scale pan and got a weight on it.
Repeated 5 times with each powder, pouring a new charge from the powder can.
My Goex 2f gave me an average actual weight of 73.7 gns. with a 1.4 gn. spread from lowest wt. to highest in the Goex series.
My Swiss 2f gave me an average actual wt. of 80.6 gns. with a 0.7 gn. spread..lowest to highest in this series.

My scale has NOT been calibrated with NIST certified weights.
Your results with your measure and your scale may differ. These are mine.  
« Last Edit: July 08, 2016, 08:55:31 PM by Don Steele »
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Offline smylee grouch

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Re: pressure difference in powders
« Reply #3 on: July 08, 2016, 09:52:53 PM »
Interesting figures Don. It made me wonder so I went and checked my note book and found that I had reduced my load 10% and not 15% when I switched from goex to swiss. This is close to your figures and shows how much difference there is in the two powders. I was also told that Old Ehynesford (sp) is also the same as swiss but don't have any to test so someone else can maybe comment on it.

Offline Mad Monk

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Re: pressure difference in powders
« Reply #4 on: July 09, 2016, 03:19:58 AM »
GOEX is what is known as a "Rifle" powder.  Swiss is a classic "Sporting" powder. 
Historically.  A sporting powder is at least 10% "stronger" than a rifle burn rate powder.  Some sporting powders were about 15% stronger than a rifle burn rate powder.


With a rifle burn rate (type) powder you usually see 75 parts potassium nitrate, 15 parts charcoal and 10 parts sulfur.  In a sporting powder, such as the Swiss, you will see 78 parts of potassium nitrate with a reduction in the charcoal and sulfur parts.  There are differences in the type of charcoal used and the fixed carbon content of the charcoal. The sporting powder will be running for a longer time in the wheel mill to give a reduced particle size of the ingredients.  Finer ingredient particle size equals faster burn rates.

All propellant grades of black powder are press densified before being broken down into powder grains.  How the grains are "polished" in the polishing drum will have some effect on the density of the finished powder.  Over the years I looked at GOEX I found its bulking density to be around 0.95 g/cc to about 1.00 g/cc.  This bulking density is also known as loading density in explosives applications.  The Swiss powder is usually up around 1.06 to 1.08 g/cc.  The Swiss simply do a better job of polishing the powder grains.  Smooth glass-like grain surfaces and highly rounded grain edges are supposed to promote better accuracy in a black powder by giving more uniform flame spreading (ignition) through the charge.  Highly polished and well rounded grains also give less variation in volume to weight when throwing charges for the gun.

Offline smylee grouch

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Re: pressure difference in powders
« Reply #5 on: July 09, 2016, 03:59:59 AM »
Thanks for that info Mad Monk. If the swiss particle size is smaller than say goex for the same designation, 2f-3f-etc., you would get more of that swiss in a powder measure weight wise. Am I reading that right or is the swiss also more dense thus weighing more?

Offline Mad Monk

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Re: pressure difference in powders
« Reply #6 on: July 09, 2016, 05:00:32 AM »
The Swiss grains themselves are more dense than those in GOEX.

In the powder manufacturing process they take "mill cake", from the wheel mill and press it.  With GOEx it is a plate and frame press where pressure is applied and air is forced out of the powder held in the frames of the press.  But that does not force out all of the air trapped in the grains.  If you were to press the powder to a maximum density it would burn too slow to be useful in the gun.
In the case of the Swiss they use a roller powder press.  The powder is spread out in  a uniformly thick layer on a moving belt.  It then goes under a roller drum that is forced downward by pressure cylinders.  Accomplishes the same thing as the plate and frame press with a lot less work in tearing down the plate and frame press to remove the cakes that look like slate slabs.

Once the pressed powder is "cured" it is ready for a rough break up before feeding into a corning mill that breaks t down into individual grains.

But powder grains directly from the press, even if dried, give poor results in a gun.  Non-uniform charge ignition.

So the grains go into the large rotating wooden barrels known as polishing drums.  The grains are tumbled in the barrel while warm air is blown through the barrel, with GOEX.  Some powder makers alternate polishing with tray drying.  As the barrel turns the grains tumble and rub on one another.  Sharp edges are rounded and surfaces polished smooth.  Given the weight of the powder charge in the barrel you get another increase in the density of the grains.  If you polish a charge of grains for 4 hours it will be less dense than a charge polished for 8  hours.  In the polishing barrel you are further compacting the surfaces of the grains.  This difference far outweighs little differences in grain size between manufacturers in the same grain size designation.

Sometime look at different lots of the same brand or several different brands.  Using a thumbnail to break a single grain of powder.  That polishing has a lot to do with how strong a grain of powder is on its surfaces.  And how dense it becomes.

But as you said. the Swiss is simply more dense.

A note on this.  If the polishing step is carried to an extreme.  In other words too much time in the barrel the burn rate will take a big dive.  The powder burning slows considerably.  There is a point in that grain density thing where suddenly the burn rate drops dramatically.  From my experience with one brand that sharp break point was 1.10 g/cc.   I had looked at a lot of firearms black powder samples from the 1800's.  Most were around 1.07 to 1.08 g/cc loading density.  I never knew why they selected that density until I got into running batches longer and getting up to or over that 1.08 g/cc "goal".  Hit 1.10 g/cc and you suddenly are faced with slow burning junk.

Offline smylee grouch

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Re: pressure difference in powders
« Reply #7 on: July 09, 2016, 05:28:03 AM »
Thank you again Mad Monk. Some people don't care about some of the tech. details but then again some do. Me included. Your participation on this forum is greatly appreciated. Smylee   :)

Offline Mad Monk

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Re: pressure difference in powders
« Reply #8 on: July 09, 2016, 05:36:34 AM »
You might want to consider looking at laflinandrand dot com and the Mutterings of the Mad Monk.  What I have explained here is found in far greater detail in those writings.

When I was doing my powder works years ago I found that actual records from old powder plants were simply not to be found.  Then I found that most powder makers had not the faintest grasp of the technical side of what they were doing.  So my writings were to explain the technical aspects of the powder making process and at the same time document the individual plants so that at some point in the future these items would not be a total mystery.

I was sort of lucky.  My every day job involved compounded plastics and rubber.  Black powder is a compounded explosive.  Very similar basics involved in all of them.

Offline hortonstn

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Re: pressure difference in powders
« Reply #9 on: July 09, 2016, 05:54:55 AM »
Thanks guys I think I'll go 10 percent less to start
Paul

Offline smylee grouch

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Re: pressure difference in powders
« Reply #10 on: July 09, 2016, 05:58:02 AM »
Yes I will be checking that link out. Thanks again.  :)

Offline Don Steele

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Re: pressure difference in powders
« Reply #11 on: July 09, 2016, 08:20:47 PM »
All our thanks to the Mad Monk.
I'm also one of those folks who likes "this stuff".
Does any of it affect my scores...probably not one little bit, but no matter. I'm a PhD Chemist and enjoy learning as much as I can about the sport I'm so involved in these days.
On that note then, thanks to a donation from our friend Moleeyes this morning I am able to report the following results of 5 charges of Olde Eynsford 2f powder that were thrown, using the same measure that I used to prepare the previous report comparing Goex and Swiss. (Note: the measure was set at 80 gns. yesterday, and has not been used or adjusted since).
As before, repeated 5 times, each time was a new "80 gn" charge from the can.

Olde Eynsford 2f gave an average actual weight of 78.0 gns. with a 2.0 gn spread between the lowest and highest wts. in this series.

I was a little surprised at the spread I got. It could easily be just personal error and a larger, more statistically valid sampling would wash it out. That wasn't my goal however. I just wanted to find out how the loading density between these 3 common powders compared and I believe we have enough information to know what we should expect, in general terms.

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Offline hanshi

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Re: pressure difference in powders
« Reply #12 on: July 09, 2016, 10:42:54 PM »
Thanks for the technical information, Mad Monk; it explains a good deal about powder behavior resulting from the milling processes.  And thanks, Don, for the very insightful test results.  IMHO, it sounds like OE is "Swiss class" sporting powder and not a "same as Swiss" sporting powder.  Both obviously are quite different from Goex.  Goex is the "30/06" of black powders; essentially the standard propellant other powders are compared with. 
While I do intend to give OE a try eventually, I've so far used Dupont, Goex, G-O, Elephant and Jack's Battle Powder.  Currently I've been quite satisfied with JBP (a Goex product available only in 3F) with Goex and JBP being my standards.  Swiss is too costly (for me) but OE is a reasonable alternative.
!Jozai Senjo! "always present on the battlefield"
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Offline Mad Monk

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Re: pressure difference in powders
« Reply #13 on: July 09, 2016, 11:56:34 PM »
Hanshi,

The OE is clearly not in the same class as the Swiss sporting powder.  Nothing about its chemistry or processing result in a true sporting type powder.  It would be more accurately described as a "good" rifle type powder.

I am fairly certain that this OE evolved out of the "premium" grade of black powder produced by GOEX before the company was sold to the present owner.  The premium grade I refer to was sold under the Express label.  I had a hand in that product.
With the Express powder GOEX ran the charcoal and sulfur mixture for a longer period of time in the ball mill.  Then when the batch went into the wheel mill they would mill it for a longer period of time.  This increased the burn rate, but not up to that of a true sporting type powder.  They had asked me to look at the Express powder to see if the additional grinding time in the ball mill and wheel mill had done what they hoped it would do.  And they were thinking back to some writings I did back around 1987 or 88 that had been passed on to them.
I took some of their regular production and some of the Express.  Broke it down in water and ran it through a 200 mesh screen.  Using soap and water to do the "wet screen" test.  Then look at the amount of charcoal retained on the screen.  With the extra grinding for the Express the amount of 200 mesh retain charcoal was considerably reduced.  Just proved a very old point in powder making that to a point, the longer you grind it the faster and cleaner the powder will burn.  I would point out it was still based on the so-called standard proportions of ingredients.

How you view a comparison of the OE to the Swiss depends on what you shoot it in.  In small caliber patched ball guns there will be a fairly big difference in velocities for the same size charge.  Then as you get up into fairly large caliber patched balls you see the difference decrease.  Then go to heavy elongated projectiles and the difference really decreases.

In the GOEX you see the 75 parts of potassium nitrate, 15 parts of charcoal and 10 parts of sulfur.  In the Swiss you have 78 parts of potassium nitrate with a lesser amount of charcoal and sulfur.  As a result.  Compared to GOEX rifle type (burn rate) powder, the Swiss produces a lesser volume of gas but at a higher temperature.  It is playing with what had once been called the "expansive force" of a powder.  In guns fired a light projectile, such as patched round balls, you want that greater expansive force.  With heavy or elongated projectiles it is more effective to use a larger volume of gas at a lower temperature.  In effect, less expansive force.

Offline Mad Monk

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Re: pressure difference in powders
« Reply #14 on: July 10, 2016, 12:07:29 AM »
Don,

The thing about the difference in weight between a series of throws from a volume measure.

Going back a bunch of years I had looked at several different volume measures in the lab.  The volume measures we use are calibrated around water.  I did not find much variation from one measure to another.

In throwing charges and weighing them we are dealing with what is sometimes known as bulking density or apparent density.  For over 30 years I ran the ASTM bulking Density test on granular PVC resins in the chemical plant.
We are dealing with highly irregular particles.  Uniform grain nesting within the measure will show a degree of variability reflected how irregular the particles are.  During the late 1800s a number of black powder companies tried to produce perfectly spherical grains of black powder in uniform sizes.  The tightest packing density would be with perfectly spherical particles of a uniform size.

That throw to throw variation you report may vary with different lots in the same brand of powder and from one brand to another.  Much depends on edges, rounding of edges and how smooth are the surfaces of the grains.

Back in the days of Windows 98SE I had a child's toy microscope I could plug into the computer and photograph powder grains.  Then after going to XP that was the end of that.  I used to photo the various lots of different brands as part of a QC program.

Bill K.

Offline hanshi

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Re: pressure difference in powders
« Reply #15 on: July 11, 2016, 01:59:43 AM »
Why, Mad Monk, do you think after coming all the way to a "good rifle powder", the manufacturers didn't take the next logical step and produce a true sporting powder?  A domestically manufactured fine sporting powder would, IMO, be very well received.
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Offline Daryl

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Re: pressure difference in powders
« Reply #16 on: July 11, 2016, 07:00:56 AM »
I am able to load 85gr. 1-1/2F Swiss in a particular case.  That same case will only hold 75.0gr. 3F GOEX.  The Swiss is more dense, ie:it has a higher specific gravity.
Daryl

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Offline Mad Monk

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Re: pressure difference in powders
« Reply #17 on: July 13, 2016, 02:12:39 AM »
Why, Mad Monk, do you think after coming all the way to a "good rifle powder", the manufacturers didn't take the next logical step and produce a true sporting powder?  A domestically manufactured fine sporting powder would, IMO, be very well received.

The 19th century sources on BP manufacture and military testing show musket, rifle and sporting type powders.  A few hints suggested that sporting type powders had been produced prior to 1800.

Black powder is considered to be a very flexible powder in that the burn rate and "expansive" force may be altered over a wide range to best suit a lot of uses.

The true high quality sporting types of black powder came into their glory during the middle years of the 1800s.  After the industry had almost fully converted over to the use of wheel mills and the powder press.  The European powder manufacturers were better at the sporting type powders compared to U.S. manufacturers.  Here in the U.S. the various powder manufacturers made their biggest profits on blasting and military type powders.  The sporting type powders represented a small fraction of their sales.

When cartridges started to come into use the sporting type powder were used only in pistol cartridges.  Rifle cartridges were generally loaded with a rifle burn rate powder.  Musket powder, the slowest burning of the 3 types, went out of production with the end of our Civil War.


Late in the 19th century the sales of black powder for use in small arms had fallen dramatically.  That was something of a kiss of death to the fast burning high quality sporting powders.  They were simply too expensive to produce for a limited and dwindling market.

The bp manufacturers were hit hard by the introduction of dynamite and safer blasting explosives for use in coal mines.

A really good sporting type powder requires very special charcoal.  Du Pont raised white willow on their plant property outside of Wilmington, DE.  After the close of the Civil War they began to buy charcoal that was a cheap by-product of the "wood chemical" industry centered in northern PA and southern New York.  I saw one price of 25 cents a bushel.  At first its use was confined to blasting powders but by WWI it was used in everything but special military powders.  When GOEX operated out of the old du Pont plant at Moosic, PA they used this by-product charcoal right up until the plant was sold to Gearhart-Owens. The last wood chemicals plant in northern PA had ceased operations at the same time du Pont was shutting down Moosic.  To produce a charcoal specifically for a good sporting powder would be cost prohibitive in this country.  Specif type of wood cut at a certain time of the year.  Then debarked as soon as it is cut.  Then aged for several years and then charred under very specific conditions.  Labor intensive.

Offline hudson

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Re: pressure difference in powders
« Reply #18 on: July 13, 2016, 04:01:06 AM »
Thanks to all and a special thanks Mad Monk for your time and devotion. I have really enjoyed this subject.

Offline Daryl

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Re: pressure difference in powders
« Reply #19 on: July 13, 2016, 05:38:12 AM »
Yes, the Monk is spot-on!!!
Daryl

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Offline smylee grouch

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Re: pressure difference in powders
« Reply #20 on: July 13, 2016, 05:58:50 AM »
I also agree, great topic. Thanks to the original poster for getting it going and to the mad monk and all the others for an interesting discussion.

Offline Mad Monk

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Re: pressure difference in powders
« Reply #21 on: July 13, 2016, 07:26:28 AM »
When I did all of the work and digging into the charcoal subject there were funny moments.
When GOEX was up at Moosic they talked about using a charcoal that was a special blend of woods.  Uh-Hu!!!

The wood chemicals industry grew up, in Pennsylvania, using second growth wood after the original virgin forests had been clear cut for building lumber.  Second growth grows fast.  These second growth trees were ideal for the wood chemicals industry.  The wood chemicals plants charred woods and recovered the various chemicals carried out of the retort cylinder vents during the charring process.  These second growth trees gave the highest yields of the then valuable chemicals.  So for profitability the charring operations mixed woods in specific proportions.  This then was the special blend the GOEX adds referred to.  Then once the last PA charcoal plant closed GOEX had to buy charcoal from the Roseville Charcoal Company with a charring operation in West Virginia.  That plant charred only maple wood and did not bother to remove the bark before charring.  During the 19th century the powder manufacturers specified a maximum ash content, in the charcoal, of 2.5%.  With the Roseville charcoal I commonly saw 5 to 10% ash content and I was told it could go as high as 15%.  The ash being the minerals in the wood and the bark mineral content is a good bit higher than the wood.  The ash simply adds materially to the fouling left in the bore.

But remember.  It would have been cost prohibitive for GOEX to get into manufacturing charcoal specifically for their small arms powders.   The big money maker were the military powders.  The military having been charged about 4 times what we were paying per pound of powder.  The military powders were not critical, in any great degree, of the quality of the charcoal used in them.

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Re: pressure difference in powders
« Reply #22 on: July 13, 2016, 05:44:54 PM »
I want to say Thanks too! I really appreciate the information and the knowledge that is shared on this site.

Richard

Offline hanshi

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Re: pressure difference in powders
« Reply #23 on: July 14, 2016, 01:41:40 AM »
Great explanation and great answer to my question, Mad Monk.  Thanks.
!Jozai Senjo! "always present on the battlefield"
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mparker762

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Re: pressure difference in powders
« Reply #24 on: July 15, 2016, 03:32:54 PM »
The fireworks guys use amounts of BP that would make us jealous, so they're a hobbyist community with reasonable experience making BP at noncommercial scales (e.g. 50lbs/yr or so).  They are making FFg BP with pine and spruce charcoal, and getting 2x the performance of Goex (hardwood charcoal gives results similar to Goex).  Swiss is more potent than Goex, but not 2x more stout.  Any idea why they're getting the results they are and why the falloff with the commercial stuff?  They're measuring the amount of powder needed to lift a given weight a certain distance into the air.  Are the commercial guys trading power for consistency and stability, or does the conifer charcoal cause other issues that don't happen to show up in a fireworks lifting mortar?

See e.g. http://www.skylighter.com/fireworks/how-to-make/high-powered-black-powder.asp
And http://www.wichitabuggywhip.com/fireworks/blackpowder2.html

The guys that are trying to make japanese style folded knives and swords are also big fans of pine charcoal over other types for their forges, claiming it's especially hot and low ash.  There's a lot of info about making pine charcoal from both groups of people.