Testing powders for accuracy

[rich pierce]

I wonder about things; sometimes needlessly. I see folks trying different powders looking for improved accuracy. I wonder about the basis for this. I’m thinking that the powder that gives the least variation in velocity would be the one to then use to develop an accurate load.

Are there other factors that would make one powder or granulation give improved accuracy?

[smylee grouch]

I,m thinking pressure curve. Some powders have a spiked peak in their pressure curve and others have a rise-plateau-drop off type of curve. Techno stuff that does make a difference.

[Pukka Bundook]

I was thinking pressure and how developed, too, Smylee.

[Mad Monk]

I wonder about things; sometimes needlessly. I see folks trying different powders looking for improved accuracy. I wonder about the basis for this. I’m thinking that the powder that gives the least variation in velocity would be the one to then use to develop an accurate load.

Are there other factors that would make one powder or granulation give improved accuracy?

When you look at this in the old literature from the 1800s they talk about uniformity of action in the bore.
Then there were some old du Pont writings where they talked about why potassium nitrate was still used in small arms powder versus sodium nitrate used in blasting powders.  They commented that only the potassium nitrate is able to give the desired uniformity of action in the bore.  Meaning pressure development and how uniform it is on a shot to shot basis.

Then I saw adds for the old Ely BP cartridge loadings done with an Austrian made sporting grade of black powder and how they claimed no more than 5 fps shot to shot differences in boxes of their cartridges.  In the end the accuracy is a result of a bunch of things.  Loading techniques play a part as do certain powder properties.  There are a lot of variables involved in how the gun prints on the paper.

Bill K.

[Chowmi]

It’s a good question. A couple things come to mind, but I don’t have answers, just more questions.

Pressure curve, already mentioned, was the first.  This may interact with the harmonics of the barrel or some such idea.

Also, I would think that the amount of fouling different powder brands or granulation, or both, create will result in a difference in velocity spread. In other words, less fouling could/should result in less velocity variation in a multiple shot string, right? 

If I may be allowed to mention black powder cartridge rifle shooting in order to bring up a point related to the question (moderators?).   In Paul Matthews book on black powder cartridge rifle shooting, he suspects that powders made in the latter half of the 19th century left fouling that was more moist than modern powder. He pulled some powder from antique cartridges and reloaded them and shot them to analyze the performance and fouling. Thus, it was easier to clear (as in when you ram the next patched ball down), as opposed to dried / baked on fouling that is hard to remove.

The point here, is that different granulation of powder and different brands may leave differing amounts of fouling, and differing qualities of fouling, which I suspect will have an effect on the velocity spread of a string of shots.
No answers, but possible reasons that these things matter.

Norm.

[smylee grouch]

I think the mad monk nailed it with there are a lot of variables involved. Stuff like how you pour the powder down the barrel, compression,size and depth of rifling,patch material and lube and I could go on and on. A lot of this info is information overload to a lot of shooters but highly interesting to others. Good question and topic  Rich.

[Daryl]

Loaded question indeed. On top of it all, is consistency of loading ALL of THE components, as smylee noted above.

Without consistency, there cannot be close shot to shot velocity and pressures, both needed and increase the gun's 'potential' accuracy.

Then after loading, the human factor comes in yet again with his or her shooting ability.  There are a myriad of potential obstructions in the way.

Sometimes, it all comes together and works.

[Mad Monk]

It’s a good question. A couple things come to mind, but I don’t have answers, just more questions.

Pressure curve, already mentioned, was the first.  This may interact with the harmonics of the barrel or some such idea.

Also, I would think that the amount of fouling different powder brands or granulation, or both, create will result in a difference in velocity spread. In other words, less fouling could/should result in less velocity variation in a multiple shot string, right? 

If I may be allowed to mention black powder cartridge rifle shooting in order to bring up a point related to the question (moderators?).   In Paul Matthews book on black powder cartridge rifle shooting, he suspects that powders made in the latter half of the 19th century left fouling that was more moist than modern powder. He pulled some powder from antique cartridges and reloaded them and shot them to analyze the performance and fouling. Thus, it was easier to clear (as in when you ram the next patched ball down), as opposed to dried / baked on fouling that is hard to remove.

The point here, is that different granulation of powder and different brands may leave differing amounts of fouling, and differing qualities of fouling, which I suspect will have an effect on the velocity spread of a string of shots.
No answers, but possible reasons that these things matter.

Norm.

Here I'll get into the thing about moist powders.
That ability to burn moist was the hallmark of C&H and other powders from various countries during the latter half of the 1800s.  You will old adds for German made powders claiming "Mit Nassbrand".  As if this were some secret ingredient.  But my work showed it is simply what wood they select and how they char it.  The present Swiss powder being the only moist burning bp in production.  Prior to about 1970 the C&H powder out of Scotland was noted for moist burning.  This property of moist burning has to do with the amount of lignin in the wood being charred and at what temperature the wood was charred at.  When charred the phenolic structured lignin is converted to other phenolic structured chemicals.  The main one here were are interested in is the amount of creosote produced during the charring process and that the charring temperature was held down below about 230 degrees.  Above that the creosote is driven out of the char and out the vent stack on the charring cylinder.  Liquid hydrocarbons produce water when burned.  Sort of an oily water.  Charcoal used in black powder that contains no creosote will not produce water as a product of combustion.  Burns dry.

A few late 1800 American powders came close to the European powders in that Nass Brand property.  The choice of wod will determine how much creosote is created by the charring of the wood.  Controlling closely the charring temperature will insure that all is held in the charcoal.  Maple wood will give you about 4% by weight of creosote in the finished char.  Glossy Buckthorn Alder will give about 12% creosote in the finished char.  I put close to two years work into that part of my charcoal experiments.

Blll K.