BP charges weight vs. volume

[B yond]

I am very new to BP shooting, and I've already made a mistake that I think I should share with the THR community to hopefully prevent someone else from doing the same thing.

I just got my first cap and ball revolver, an 1860 army repro by Uberti. I was very anxious to get it out to the range and shoot it,but didn't have a BP flask or measure, so I took my bottle of triple 7 FFFg and my reloading scale and measured out a bunch of 20gr. charges and rolled up some paper cartridges.

Went to the range and luckily everything went well; lots of smoke and boomage.

I just learned that BP charges are supposed to be measured by volume not by weight.

I went out to my reloading bench measured out another 20gr. charge of triple 7 by weight and checked the volume on it: approx. 30 gr. (max. recommended charge from hodgdon is 25 gr.)!

So while I thought I was using a low-end charge I was actually pushing closer to the limits of what the weapon could handle, and I didn't even know it.

The moral of the story: BP is measured by volume, not weight, and always do as much research as possible before trying out something new. I though I knew what I was doing because I'd read a few BP threads and have some reloading experience, but I was wrong. I'm just glad my gun wasn't harmed and I still have all my fingers.

 

[whistler]

wrong black powder is measured by wieght.
777 is lighter than black powder when measured by volume but has same power when measured by volume.

 

[mykeal]

Actually, you weren't in any danger. Even a chamber fully loaded with 777 will not damage one of the current (steel framed) bp revolvers. Now, if it had been smokeless powder, the results would have been very different.

30 gr of 777 is equivalent to almost 35 gr of real black powder. I suspect a good deal of the powder was consumed outside the barrel. Must have been a good show.

That load would be entertaining, but probably pretty inaccurate. The real issue here isn't damage to the gun but damage to your accuracy - you won't win any contests with that load. Also, although the gun was unscathed, I wouldn't make a practice of using that load in that gun very often. Over time (hopefully, a good long time) it could damage the frame a bit.

So, good lesson, no harm done.

Whistler said:

wrong black powder is measured by wieght.

Huh? Since when and by whom? What metric are those little brass powder measures we all use actually recording?

 

[B yond]

777 is lighter than black powder when measured by volume but has same power when measured by volume.

According to what I've read, the 777 charge has to be reduced by 10 to 15% to match the velocity of a BP charge.

 

[whistler]

black powder is measured by weight.What do you think the 30gr. means and the marks on your brass measure stands for the volume equal of weight .that is why it's marked grains.Grains is a measure of wieght
not volume.

 

[Jeffreii]

BP is measured in grains (weight), however, the new "replacement" powders such as pyrodex and triple se7en are altered to make the VOLUME the same, not weight. If you use REAL bp, you can use either type of measure, if you use a "replacement" then you have to go with volume, or use weight with the appropriate "correction factor."

The BP measuring devices that list grains, are the grains if the powder is BP. Since the substitutes for BP are equivalent to it by volume, you can use them too, although the actual weight will be less (I am not aware of heavier-than-bp substitutes) than the grains listed on the powder measure.

 

[B yond]

BP is measured in grains, however, the new "replacement" powders such as pyrodex and triple se7en are altered to make the VOLUME the same, not weight. If you use REAL bp, you can use either type of measure, if you use a "replacement" then you have to go with volume, or use weight with the appropriate "correction factor."

Bingo. That's the point I was trying to make.

 

[Pancho]

Jeffreii, that was a good explanation. I wonder when the old boys worked out their charges if they used a scale to decide the gr. their gun would shoot and then make a charging container that would hold the preferred charge used in the gun. usually the hollowd out horn tips

 

[Pulp]

This seems to be a problem many folks can't quite get the handle on. Even smokeless powder is loaded by volume if you use any type of auto powder feed, you are loading by volume. You fiddle with the volume until it throws the weight you want. Then the feeder throws the same volume each time.(Hopefully. That's why you should check every 10th load or so.)
I often see a term like "35 grains volume". There is no such measure. Grains measure mass, and volume measures space. The proper term would be "35 grain volume equivalent", which means the volume of substitue BP thrown is equal to the volume occupied by 35 grains of BP.

 

[pohill]

how about this:

http://hunting.about.com/od/reloadinfo/qt/qtmeasurepowder.htm

 

[mykeal]

Whistler said:

black powder is measured by weight.What do you think the 30gr. means and the marks on your brass measure stands for the volume equal of weight .that is why it's marked grains.Grains is a measure of wieght
not volume.

I know that the markings on a bp powder measure imply that filling to a given mark with real bp will, within some error band, result in a volume of powder that weighs, in grains, what the mark says. I also know, from simple physics, that the measurement is in fact a measurement of volume. There is no mechanism for determining the weight of the powder using that method; we are simply making an approximate translation and incorrectly using a weight (mass) metric to describe a volume measurement.

The use of 'grains' to describe the volume measured has become common practice over the last hundred years or so, enough so that the term is now considered a volume metric in the context of black powder shooting. Common usage within a certain context dictates meaning in public discourse, regardless of formal classroom dictum.

You correctly describe how we came to use the word 'grains' in describing an amount of propellant. But the common usage has, within the context of the black powder discourse, superseded the original meaning of the term, and it now describes a volume measurement when used in that context.

 

[Jim Watson]

Not in MY context. I weigh every load of real saltpeter black powder that goes in my Winchester on a scale in grains avoirdupois. But that is for BPCR match shooting.

I measure a lot of my smokeless in a volumetric measure for convenience and speed, just like the ammunition factories, but it is adjusted to deliver the desired weight.

The black powder fakes are of lower density and as said, are mean to be loaded in a volume that would contain a given weight of some mythical average black powder. Somebody once set a volumetric measure at "100 grains" and carefully ran several different brands and granluations of real black powder through it. He got powder weights from about 90 to 115 grains. He had a good technique and weights were consistent for the same brand but differed widely from Goex to Swiss and from Fg to FFg.

That is not a major liability for casual use or if you are willing to tinker with the measure and stay with the same brand and granulation of powder once you have found a good load. But I want to know what is going on, so I use a scale.


"If you call a dog's tail a leg, how many legs does a dog have?
Four.
Calling a tail a leg does not make it one."
A. Lincoln

 

[pohill]

I know that a given caliber designates how many round balls per pound of lead, but how did they (Colt) determine what exact size of roundball was most effective? Then it would follow that once you have a ball size, what charge of BP is most effective in propelling it a given distance. And once you have that BP charge "worked up", how do you measure it for consistency? I'd say that out in the middle of the wilderness, measuring BP by volume made more sense than by weight, especially given that any excess BP would be blown out the barrel, which is not the case with smokeless, which might blow the barrel out - correct? How, why and when the measure of grains was applied to volume is one of those mysteries.

 

[whistler]

ok now to get things mixed up. what about deferent brands of black powder that are pressed to different densities and the different grain sizes like FF and FFF that will not weigh the same per volume.

 

[Macmac]

I have "read" first hand accounts, which appear to me for a "General Rule of Thumb" in days yonder, that the bore size was the charge size in long guns.

I can see all sorts of flaws in this thinking, but it still seems to be true in long guns.

So by this rule most hand guns won't even take that much, but in long guns it will seem a mid range charge.

So what ever calibur you have a middle road charge is the caliber, by old standards.

One of my long Guns is a Curly Deskomski (sp) Nor' West Gun, a trade musket and 0.62" bore. This shoots a 0.600 round ball patched and or any kind of shot. So a middle of the road charge is 60 grains by volume in real (2)FFg BP.

This could be a hunting load, but as much as 80, and as little as 40 grains of the same work. On paper targets I almost always use apx 40 grains, which atleast in this particular gun is fairly accurate.

Some how I think it would be a problem getting 45 grains in my ROA and have room for a round ball. Maybe I can, but I never tried, as for me on paper 18 grains by volume and a little filler works fine.

I use this same charge in my 1860 colt clone by EMF as well, since I pretty much don't hunt with hand guns of any kind.

 

[ED21]

It's not that difficult. Don't try to think it to death. USE VOLUMN only when dealing with Black Powder or the substitutes. The use of the term "grains" is used as a reference so we know how to mark our measures. Don't try to confuse the issue.

 

[Bad Flynch]

Actually, no one has it right. Black Powder is, historically--and still is---, measured by volume. However, it is not the volume of which most people think.

BP is measured in water volume grains, a combination method. What is done is to measure out, say 60 grains of water. One simply shoots the same volume of BP as the 60 grains of water occupied to get a 60 grain charge of BP.

We have to go through this every few months, as people forget and new people come in.

This was done so that there could be some easy method of measuring BP in the field and that the standard, water, was the same everywhere. Can you imagine trying to weigh out a powder charge in the heat of battle? Neither can I! Note that this standard is not depedent on who manufactured the powder, either, or what granulation it is.

In modern ballistics calculations, one still measures case capacity and bore capacity in grains of water--although that may eventually be converted to metric volume measurement for ease of calculation.

 

[B yond]

B.F. that's very interesting, and sounds good. Do you have any kind of historical reference to that?

Not arguing, just asking. I'm becoming a bit of a history buff and would like to read up on it.

 

[mykeal]

Bad Flynch - thanks. You're right. I had forgotten that. I recall reading it someplace. I'll try to find it tonight.

 

[Bad Flynch]

B.--

Histerical references you want? Hmmm..

I wish that I could tell you where this came from, honestly. It has been with me for so long that the source is long lost. You may be able to find it in one of the modern BP compendia, like the one Sam Fadala authored, Lyman published, etc. It might even be in the DGW catalog. I have about 300 shooting books, so I'm not gonna find it soon. For so many years, all of the "modern" shooting books and authorities ignored BP althogether. It has only been since the 1970s and the BP resurgence, what with primitive weapons seasons, that this has become an issue. The issue is more that modern shooters have not been exposed to the methods of the past because of insufficient education and the publications that ignored the issue.

Think about it, though. 60 grains of water (or any arbitrary amount) always weighs the same and always has the same volume. It is a convenient and easy standard the world around. Although I did see one time that some countries did not use that standard like we do. Those other countris may now use it, however.

I suggest that you write the NRA technical staff; they should be able to find a reference. If I run across it, I'll try to find this thread and contact you.

 

[Pulp]

"I know that a given caliber designates how many round balls per pound of lead,"

Caliber is one/hundreths inch. Gauge is what you're describing.

 

[w_houle]

I remember reading that you thake the bullet in question and put on the palm of your flat hand and cover it with black powder, take your middle finger to hold the ball in place and pour your charge in the barrel. In that instance I would think that bp is very forgiving in how you can load it

 

[Bad Flynch]

>I know that a given caliber designates how many round balls per pound of lead,...<

Well, most of the answer to this one has been covered and yes, it is gauge. However, when talking about the "Bore" of a shotgun, I have always assumed that the term "Bore" is the same as the term "Gauge." Well, maybe it is -- in the U.S.

It turns out, that some European countries that were on the metric system for a long, long time, used the term "Bore" to designate the number of balls per Kilogram (2.20 Lbs). Just learned that today and do not necessisarily know how to process that into practical information. These balls would weigh 2.20 times the weight of ours for the same "Bore" designation. I am assuming that the radius of the ball would be increased by something like the cube root of 2.20. If my calculator worked right and I have my math right, & just off the top of my head, that would be an increase in the radius of a factor of 1.30059 for the same designation for the Kilogram system.

 

[Jeffreii]

Thanks for the info B.F.!

So BP was really measured in "weight", but they use volume tools as a means of getting that weight, being evident by using units of weight rather than volume. Confusing - but it does make sense if you realize that BP weapons were "loaded in the field" - not the case for cartridge rounds.

Measuring by weight seems to offer more concise measurements of the relatively small volumes of gun power in small arms. A scale can pick out a .1 gr difference a lot easier than the volume methods since the substance (powder) is not a liquid or real fine powder. The profile of the top of the powder is to variable. However, that is not the case if you load in the field - you can't have your scale with you...lol. Being needing to load up "in the field" would require volume measuring, and water as a reference makes perfect sense as it is commonly available and static in density enough for their purposes. Water is used all the time as a baseline for comparing just about anything you can think of.

I read about using water as a baseline for measuring grains with volume and using the density difference as their standard - I think it was in "Understanding Firearm Ballistics" [ISBN 0964559854] if I remember correctly. I will check and see to make sure. Too many books, too much to know, and not enough time. What's new.

 

[Pancho]

As I imagine it,when our forefathers bought a gun the smith had proved it at the shop with various loads measured by weight in grains. Knowing that the buyer would not be able to load in the field based on weight the smith would make a proper dipper that would hold the preferred weighted charge. The volume based adjustable measures availiable to us to day are based on that conversion made 100's of years ago. I've never done it but I'd wager that if you took a graduated volume measure that we use today and add BP to say to the 30 grain mark and then weighted it it would weight 30 grains
Now speed ahead to the 20th century. We have the same old powder companies wanting to produce new powders for the market and they need a way to compare the new powders to the Black Powder benchmark.
The question in there minds would be how to compare them,by weight or by volume. The powder companies knew that at the time the major users of blackpowder and the substitutes used volume to measure their charges. It is my belief that the powder companies were smart enough to formulate their powders to be compared by volume to black powder because we shooters were used to using volume in the field. It wasn't until the Cowboy action appeared that there became a problem. They routinely loaded there rounds at home on their loading benches and were taught to use weight to measure their loads. Now this is still accurate if one is using black powder but if you want to use the subs you're going to have to use volume to attain a comparison because the manufacturers used volume to create a powder comparable to black powder loads The fly in the ointment in 777 it is so much lighter and hotter than BP that you must reduce the amount of 777 by 15% by volume.