Mixing Powder

[Britsmoothy]

Brit,
In the quotes above, It is made plain that Long , and Narrow charges of fine powder were the problem in point. (145 grains in a .45.)
You ask why we do not see problems with Bill Ruger's Revolvers; This is for two reasons, and the blindingly transparent one is that you Can't fit that much powder in a revolver!
( 30 to 40 grains is all you can shove in most.)
The Second reason is because in a revolver, as soon as the ball is in motion, there is a sudden pressure drop as it transfers between cylinder and barrel breech.

Re. what powder does when it "goes off";

Deflagrats was not used in the era of which we speak. To them, if rammed tight and one end was consumed before the other, which was then crushed into a solid behind the projectile, this could cause a "detonation".
Call it what you will, the result is very much the same.

I won't be adding any further comments to this thread.
My only reason for saying what I have is for safety reasons.
It was proven over 100 years ago that fine grained and fast burning powder could cause a pressure wave that would blow a gun to hell In the Right Circumstances.
I have given the quotes and the test results.
What you chooses to do with this information is entirely up to you. It's now off my chest!

All the best, take care,

Richard.

Thank you Richard.
Re the revolver, like you point out, small amounts can only be loaded.
Exactly what I have recommended and repeatedly so.
The next comment I wish to address is the powder under compression is now a solid mass you said or implied.
So now we don't have 4f, we have a solid piece of which only a small amount at the rear is burning! Hmmm, I think my work is complete here also.
All the best.

B.

 

[Felix the Cat]

Ah.. I seem to have stepped into something of a stramash here as they say in my part of the world..

May I make a few observations.. Firstly black powder does not detonate.. it, as smoothy points out, deflagrates which means in simple terms that a flame front surrounds each powder grain, which burns down like a lump of coal until nothing is left. Detonation is an entirely different process which has a supersonic shock wave passing through the mass of explosive, disrupting it at a molecular level. Many nitro based propellants are capable of both deflagration and detonation. Black powder, because of the solid content, will only deflagrate. What can happen however is that if there is sufficient air space, you can significantly increase the burning rate of black powder by shattering the grains, increasing the surface area. There is also some speculation that the oxygen in the void will be used to increase the effectiveness of the burn, as there is always excess carbon available..

I have repeated the copper tube experiment a number of times, and there is definitely a pressure pulse if you leave an air gap in a gunpowder charge.

As to mixing powders, it is the density of the particle that is the factor in separating grains in a mixture rather than the size. The original purpose of corning gunpowder was to combine the ingredients into a single grain so it would not separate out in transit. All black powder is a mixture of grains of different size, it is graded by passing through sieves which filter out the larger particles. the grain size is pretty arbitrary. Corned gunpowder is made up from grains made by compressing very fine "meal" powder which is released when the grain structure is damaged. Common pointed shell used to be filled with a mixture of grain sizes from pebble down to sweepings. There is little evidence it separated out..

does this help, or have I just stirred the pot?

Just to throw a few more rocks into the pond.. this is quite interesting if you are interested in medieval gunpowder..

 

[Pukka Bundook]

Felix,
Though I have said what I set out to, I must just point you to the previous page where I was quoting Greener Re. pressure wave, and "detonation". His term.
All the very best Felix,

Richard.

 

[Britsmoothy]

Dear Richard.
Mr Greener was a very talented engineer amongst other attributes but he was not a god!
Just a man and prone to mistakes like all of us. If we remember this we assume less!

ATB

 

[George]

Greener? Did someone say Greener? A W.W. Greener:

Spence

 

[Felix the Cat]

Greener was an excellent gunsmith and businessman and held many strong opinions, not all of which have stood the test of time! This is not to say that much of the mid 19th C research work is to be ignored. As Kay Smith said in her lecture, not much research has continued, at least in the public sphere, into gunpowder since the 1880s when attention shifted to nitro powders. As some on this board have commented, you need to look at where opinion is based on evidence rather than emanating from the depths of an armchair..

Capt F M Smith RA, assistant superintendent of the Royal Gunpowder Factory, Waltham Abbey in his 1870 "Handbook of the Manufacture and Proof of Gunpowder" points out that there are many factors affecting the performance of a specific charge. He makes the point that there are two distinct and potentially competing processes going on in a firing charge that depend to a greater or lesser effect on the grain size. These are the rate of ignition and the rate of combustion.. Smith defines "ignition" as the progress of a flame front through the charge, igniting the surfaces of the grains. He suggests that in coarser powders, there will be greater space between the grains, allowing the flame front to progress quickly through the mass of the charge, whereas with a fine grain, the spaces between the grains will be less and the process impeded.

Once a grain is ignited, it will burn at right angles to the surface of the grain, reducing in size until the grain is finally consumed. The rate of combustion will depend on a number of factors including the initial charge temperature, the pressure, the nature of the ingredients, particularly the charcoal, and the density of the grain. All things being equal however, it is the surface area of the grain that is the main determining factor, fine grain powder having a larger exposed surface area than coarse grain.

In practice this means that we have two competing processes in play during the burn. Coarse grains having a lower rate of combustion, but a higher rate of ignition, and fine grains having a higher rate of combustion, but a lower rate of ignition!

This is nicely illustrated by some trial results! You need to understand that in the 1870s the RGF only produced a limited range of gunpowders, mainly "RFG" - Rifle Fine Grain for small arms and "RLG" Rifle Large Grain for medium calibre cannon. Large calibre cannon was by this time fed with pressed "Prism" and "Cocoa" powders made from brown coal and straw charcoal in an attempt to reduce the burn rate.

Firstly some trials with RLG - a 1lb charge behind a 12lb shot ..

Grain size Velocity
4-6 976 fps
6-8 1001 fps
pass 8 1015 fps
Velocity increasing as grain size reduces... combustion effect greater than ignition effect.

Now a heavier charge behind a lighter projectile.. 1.75lb charge behind a 9lb shot..

Grain size Velocity
4-6 1410 fps
6-8 1369 fps
pass 8 1292 fps
Velocity decreasing as grain size reduces.. ignition effect greater than combustion effect!

For completeness, he also gives illustrations of small arms performance:

Special RFG - 70gn in a Snider Enfield:

Grain size #grains in 10gn Velocity
12-16 326 1039 fps
16-20 626 1088 fps
20-24 1072 1111 fps

Special RFG - 83gn in a Martini Henry:

Grain size Velocity
12-16 1245 fps
14-20 1256 fps

Special RFG - 90gn in a Martini Henry

12-16 1287 fps
14-20 1298 fps

So... it depends! Predicting Black powder performance is clearly not straightforward, and will depend on many factors, not least the chamber of the gun and the batch characteristics of the powder... The only way to find out is by firing trial per batch and per gun type.. which is what has been done by the military for over two hundred years!

It is also interesting to see the limited effect of grain size on velocity. Quartering the size of the grain has less than a 60 fps difference in velocity..

I remember being told that the way to fly a helicopter is to fight the beast off the ground by waggling every lever in sight. Once off the ground, stop waggling and look to see what the chopper is doing, because if you want to do that again, that is where you need to put the controls...

... buy a chronograph and use it!

 

[Britsmoothy]

Thank you Felix.
Your concise reply is what I wished for all along and is far better than playground dicourse!

The information backs my findings.

Large grains in my guns blows patterns more than fine grains. Because (as I have always believed) it is still peaking in combustion to near the muzzle!

 

[Felix the Cat]

Thank you Felix.
Your concise reply is what I wished for all along and is far better than playground dicourse!

The information backs my findings.

Large grains in my guns blows patterns more than fine grains. Because (as I have always believed) it is still peaking in combustion to near the muzzle!

Whatever works for you is good..!

My experience is more with solid projectiles than shot, although I shoot both muzzle and breech loading shotguns. Pattern formation is not an area I have strayed into so I must hold my hand up here. I know something of the fun and games getting sabots to release on tank projectiles, but this is probably not directly applicable..

But yes, the "all burned" point is a significant factor in ammunition design. Ideally it should be in the first half to two thirds of the barrel. It is however difficult to control the burning rate of Black powder. This is why, apart from the limitations in metallurgy, muzzle loading cannon of the late 19th C had massive breeches and short barrels. The US Parrot gun was a clever use of a wrought iron/steel band reinforce around the breech of the cast iron barrel..

 

[Pukka Bundook]

Felix,

I do not know whether you started at the beginning of this thread, if not, please go back to say post number 30 and work forward.

Brit smoothie is still maintaining that 4 F can be used as the main charge;
It may well work, (but not best) Most of the time, but in maintaining this stance, he is ignoring the Pressure tests done with cartridges that were loaded with fine -grained and fast burning powder, That produced Three Times the pressure of the same cartridge loaded with rifle powder. These cartridges blew the rifle into atoms.

This is not Playground discourse as Brit so simply puts it. It Is Fact.
Whether the cartridges were tested By Greener, or at one of the proof houses in the UK I do not know, but to Ignore these Facts just to save face and safeguard ones own point of view, I find staggering.
Brit challenged Anyone to produce Proof of fine grained powder causing enough pressure to damage a barrel. I supplied proof of this Very Thing happening.

What he or anyone else does with the information, is entirely up to them, so I suppose Ignoring as inconvenient to ones argument these facts
is more than just a possibility!

Stay safe.
Pukka.

 

[Britsmoothy]

Felix,

I do not know whether you started at the beginning of this thread, if not, please go back to say post number 30 and work forward.

Brit smoothie is still maintaining that 4 F can be used as the main charge;
It may well work, (but not best) Most of the time, but in maintaining this stance, he is ignoring the Pressure tests done with cartridges that were loaded with fine -grained and fast burning powder, That produced Three Times the pressure of the same cartridge loaded with rifle powder. These cartridges blew the rifle into atoms.

This is not Playground discourse as Brit so simply puts it. It Is Fact.
Whether the cartridges were tested By Greener, or at one of the proof houses in the UK I do not know, but to Ignore these Facts just to save face and safeguard ones own point of view, I find staggering.
Brit challenged Anyone to produce Proof of fine grained powder causing enough pressure to damage a barrel. I supplied proof of this Very Thing happening.

What he or anyone else does with the information, is entirely up to them, so I suppose Ignoring as inconvenient to ones argument these facts
is more than just a possibility!

Stay safe.
Pukka.

Richard, my apology. I most certainly was not refering to you in my "playground" comment. You have not used insulting speech at all.

I did however think I had made my view on Mr Greeners a account clear.
The account does not (I understand) describe accurately what the powder was other than "fine".
I then suggested that some are assuming it to be akin to 4f, we can't assume that, we don't know that!
For all we know it could of been caused by something completely different, we don't know.
Put differently, in a court of law it would not be able to stand a measure of cross examination.
This has nothing to do with a personal agenda by me. In fact it is me before many a critic and some insulting comments (of which one has continued privately) that has asked for scientific data.
Scientific data could equally correct me or qualify me, in others words I want to hear truth on this matter.
Opinions are only any good if can be proven. I can't prove it academically either way, I only offer little load data by others and submit my own experiences using fine powder against all conventional trends.
I am surprised you have taken this personally for which I apologise.

B.

 

[8 BORE]

Brit Smoothie
Somebody else fineally figured out thst you ate nuts

 

[Felix the Cat]

Felix,

I do not know whether you started at the beginning of this thread, if not, please go back to say post number 30 and work forward.

Brit smoothie is still maintaining that 4 F can be used as the main charge;
It may well work, (but not best) Most of the time, but in maintaining this stance, he is ignoring the Pressure tests done with cartridges that were loaded with fine -grained and fast burning powder, That produced Three Times the pressure of the same cartridge loaded with rifle powder. These cartridges blew the rifle into atoms.

This is not Playground discourse as Brit so simply puts it. It Is Fact.
Whether the cartridges were tested By Greener, or at one of the proof houses in the UK I do not know, but to Ignore these Facts just to save face and safeguard ones own point of view, I find staggering.
Brit challenged Anyone to produce Proof of fine grained powder causing enough pressure to damage a barrel. I supplied proof of this Very Thing happening.

What he or anyone else does with the information, is entirely up to them, so I suppose Ignoring as inconvenient to ones argument these facts
is more than just a possibility!

Stay safe.
Pukka.

Hi Pukka,

I was trying to inject a little stability into the discussion.. As I am sure we all agree, there are some phenomenon associated with propellants which are complex, difficult to reproduce and even now, not fully understood. There is also a problem that the received wisdom based on nitro powders and that from Black powder sometimes gets mixed up in folk's mind and assumptions about one do not cross over to the other.

Can I firstly deal with the issue of "detonation". I am aware this is the term used by Greener, however since his time there has been a better understanding of the phenomenon and a tighter definition. As I explained in my earlier post, detonation is a specific phenomenon which is the result of a chemical reaction associated with a supersonic shock wave. Most compounded propellants and some mixtures are capable of reaching detonation, however it has never been successfully demonstrated in Black Powder(BP).

This is not to say that BP is not capable of producing pressure peaks under certain conditions. It would appear from recent(ish) research (R A Sasse, Aberdeen Proving Ground, 1988) that this is associated with grain fracture, exposing a large surface area. This research was based on investigating the performance of BP in artillery cartridge primer magazines however does seem to give insight into the phenomenon. Simply put, if BP grains are allowed to impact a surface during an ignition event with sufficent energy to break up the grain into fine powder, then the pressure can peak. This is certainly a way to understand the need to ensure BP is in a stable mass with no air gaps in a charge system. You do not want propellant grains being allowed to build up velocity within a gun chamber and impacting on the base of the projectile..

With reference to using fine powder as a main charge, then I agree this is going to result in higher pressures than with a coarser propellant. There is also the issue of a fast burning charge building up pressure quicker than the inertia of the projectile can cope with. In order to keep chamber pressures within limits, the projectile has to start moving to allow the pressure to drop. In some designs, such as revolvers, there is a need to reach the all burned point almost before the bullet starts to move as the chamber is of limited length, however this is known and the chamber designed to cope with the peak charge. At the other end of the scale we have shotguns which have very thin chambers and low working pressures which rely on a low starting inertia for the shot/wad combination which has to move quickly to allow the capacity of the chamber to increase and allow the pressure to drop. In these cases the propellent is designed to burn at low pressure..

A confusion arises in some cases because of a"dragon at the back of the cave" issue with small charges of slow nitro powder in large chambers. Again this is a difficult issue to resolve, as it is hard to reproduce! In this case however it would seem that detonation may indeed be the cause. The closest working theory proposes that if large lumps of slow burning nitro powder are allowed to accelerate down an empty chamber and impact on the base of the projectile, then the grains will detonate and blow up the chamber. Detonation occurs at something like 5km/sec which exerts a shattering effect on metal. You can easily demonstrate that nitro powder is capable of detonation by using a detonator/blasting cap in a charge of nitro. You can also demonstrate that is does not occur with BP! Can I also say that this phenomenon does not occur with small charges of fast powder as the powder is all burned before it can impact the base of the bullet!

So chaps, can we agree that using ultra fine priming powder (FFFFg/Special OB) as a main charge is not a wise thing to do! BP is much less pressure dependent than nitro, however both can suffer from runaway pressure reactions. That said, I always have a small plastic bottle of the stuff for priming and sorting out misfires. I refer to it as "Oofle Dust" (which will only make sense to Brits of a certain age!) It has never failed to clear a blocked vent or oily nipple!

 

[Britsmoothy]

Brit Smoothie
Somebody else fineally figured out thst you ate nuts

At last something you and I can agree on.
I am nuts. And I eat them.
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