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Old March 7, 2019, 04:13 PM   #26
prof marvel
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My Good Thallub -

thank you for the civil and direct response!

I see you have read Bill's writings also

My personal experience differs from yours. from 1972 until the mid 1990's i used BP exclusively since it was readily available from several specialty shops as well as "over the blanket" at the several rondy's I attended . The worst BP I ever shot was a particular batch of Elephant that (after the fact) was acknowledged to be terrible at fouling. Bill opined that they , like Goex had gone cheap on the charcoal.

After the 1990's, BP became harder to get, and the number rondys in my area diminished. I started using Pyro, found it hard to ignite, and found the guild of professional builders who tested it extensively. As a result of that and the guilds findings of "chamber" erosion I decided to use Pyro only in firelocks that I could break down and clean very well, end-to-end. That way I saved my BP forcaplock and flintlock rifles, and I use Pyro in my revolvers and Sharps papercutter with a small BP booster. The other advantage to the Sharps is that I can fabricate and replace the chamber if I ever need to. (also, it's a cheaper italian copy)

Many, like yourself, believe this stuff is not "rocket science" . Yet, at the end of the 19th century, with the primitive tools available, ballisticians and chemists were making findings regarding gunpowder that seem to have been forgotten or ignored today.

For example:
- wavefronts.
It is well known that when gunpowder is ignited, the expanding gasses make a so-called "blast wave". what is less discussed is that the gun barrel acts as a pressure vessel with a rapidly expanding volume, and that gunpowder (and smokeless, I am sure) can and will under the correct conditions create high velocity reflecting wavefronts that travel back and forth and if multiple wavefronts coincide this can cause enourmous pressures. This was studied extensively in large Naval Guns but was demonstrated on a smaller scale in some small arms.

-burn rates and pressure
The "common knowledge" is that BP won't blow up your gun - ie it can't build pressure beyond around 15k or 20k cup depending upon who you talk to. I seem to recall, (but cannot find the source) that some late 19th centruy Europeans in the quest for large bore velocity, were reaching 40k ish cup or more but did not get the velocity desired.

The Lyman BP book shows a wide spread of pressures from ~ 13k to ~23k psi using the same load, same projectile. Substitue powders can increase pressure even more. Not surprising as they "burn hotter".

Burn rates were said to be constant.... until they weren't. variations in circumstances seem to cause odd anomalies.

Burn temperatures do not seem to be discussed.

And of course the closed vessel tests achieved pressures in excess of 100k "units said to be psi".... but that is yet another different scenario and discussion.


- chemistry
As The Mad Monk pointed out many times, the best charcoal produces the least fouling.

Other folks have added various things to try to make BP better. Plain sugar, iron oxide, fulminates, and potassium perchlorate amongst others.

The perchlorates are popular, since they provide both stabalization ( for which I am eternally greatlful!!!) and an increase in expansive gasses, thus more oomph. Unfortunately amongst the side effects are that they are harder to ignite in some firelocks; burn hotter and more agresssively; and deposit perchlorate salts. I am still researching what happens to the cyanides. These and the different "burn chemistry" can lead to different corrosion results.

Some additives seem to be stable, some not so much - witness your experience with unburned BlackMZ corroding your bore!

What has not been researched and discussed at length (to my knowledge - but I have been wrong before and expect to be wrong again) is the chemical processes that occur
upon ignition and combustion of these differrent compounds.

In some ways, this actually IS rocket science, since some of what we know of BP and much of what we know of sugar-based fuels comes from solid-propellant rocket reasearch dating back to Robert Goddard. That research however is more concerned with thrust, nozzle design, and "not exploding" and no one cares about corrosion since the engine nozzles are considered somewhat expendable.

I respect your education, applaud your open mindedness, appreciate your considered reply, and am interested in your tests!

I am continually amazed at how people have different experiences, but I am convinced by my many years in complex failure analysis that the variations in conditions are the key, thus the need for continuing conversations!

yhs
prof marvel
(please forgive misspellings & such, my brain is not getting along with my fingers so well as of late)
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Last edited by prof marvel; March 7, 2019 at 04:30 PM.
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Old March 7, 2019, 04:48 PM   #27
prof marvel
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Quote:
Originally Posted by thallub View Post
Prof Marvel:

My research and personal experience means nothing to the "experts".
your bonafides and experiences are as important as any "expert's" . More interesting scientific achievements have been made by "talented amatuers" than I care to mention.

Quote:
Yep, Mad Monk is an interesting guy but he gets things wrong sometimes.
oh my yes, and I get more things wrong than I get right, but I am continually trying to learn from my mistakes and improve. BTW Bill's ablility to analyze BP using kitchen methods are remarkable!

Quote:
i'm looking at a cheap CVA rifle bought in 1999 or 2000. That rifle has fired at least 3,000 rounds using Pyrodex. The bore is like new. That rifle has never been cleaned with hot water and soap. My rifles are cleaned using patches wetted with tap water-period!!!
Obviously water works! Since I am cheap er frugal and near-sighted, and I have experienced the strange Pyrodex rust blooms after cleaning , I tend to err on the excess vis-a-vis scrubbing.

There are apparently cheap chinese electronic borescopes available that plug into a computer. Are you able to borrow or acquire such a thing and examine themagnified internal breech area ? The more real-world data we can discuss, the better.

Quote:
Today most of my muzzleloader shooting is with Black MZ that contains a big slug of potassium perchlorate. During hunting season my guns sometimes go uncleaned for weeks. i've never had any problem with rust.
Please forgive the dumb question, but "uncleaned for weeks" after firing?
have you treated your bore in any way, or is this bare steel?

Quote:
The residue from firing Black MZ is less corrosive than the unburned powder itself. The bore of a gun loaded with Black MZ for a prolonged period of time will often have crazing and very small pits where the powder sat.
whilst I plan to, I have not used BlackMZ yet, but your experience with the residue echos that of several of my friends. This makes me wonder about the differences during the burn.

Quote:
i've done my own tests on steel plates. My results were similar to photos posted by rodwhaincamo.
Since such plate tests are not under "chamber pressures' the results may differ from
tests in a gun barrel. However, all data that is carefully recorded and reproducable is good data.

Do you still have the plates? have you or can you examine them at 40x or above? I am particularly interested in microscopic level erosion.

thanks for any replies
yhs
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Old March 7, 2019, 06:40 PM   #28
thallub
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Thanks Prof Marvel.

i got seriously into muzzle loading in 1965 after making friends with a black powder gunsmith, marksman and collector. The only propellant available was black powder. i used DuPont powder. Never had any problem with DuPont powder.

Quote:
I am still researching what happens to the cyanides.
i've never heard an explanation for that.

Some say the Pyrodex formula has changed over the years. The Pyrodex patent listed dicyanamide(6 percent). The current MSDS does not list dicyanamide.


BTW: The latest MSDS for Triple Seven lists sodium nitrate.

https://www.hodgdon.com/wp-content/u...en-sds-new.pdf


Quote:
Please forgive the dumb question, but "uncleaned for weeks" after firing?
If the weather turns rainy the gun is cleaned. Sometimes there is thin rust on the patch but the bore cleans up nicely. The consistency of the residue of Black MZ sometimes varies. i'm a patched round ball shooter. Sometimes the residue acts like an lubricant.

Quote:
have you treated your bore in any way, or is this bare steel?
Bare steel.

My test plates are long gone, used up in a welding project.

Give Black MZ a try soon. The lowest standard deviations i recorded were with Black MZ. Black MZ is not being manufactured and will be gone forever.
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