Black Powder - V: Powder Grain Sizes in 19th Century England

In our last post, we looked into how black powder grains are classified by size and type in the US, from the 19th century onwards to the present day. In today's post, we will look at the classification of different powder types in England in the 19th century.

It must be remembered that before the invention of smokeless powder in the latter part of the 19th century, people used black powder for everything from the smallest pistol to large cannon. Therefore, they had to have different types of black powder to accomodate all these weapon types. In England, smoothbore weapons were used as well as rifled weapons. For instance, the Brown Bess musket (which is a muzzle loading smoothbore weapon) was produced by the British from 1722 to about 1860 or so.

We noted a couple of posts ago, that the average size of the grains is a huge factor in the combustion rate of gunpowder. With the introduction of rifled guns, it was considered a good idea to use a powder that would burn more gradually and strain the gun less, than the powder then in use for smoothbore guns. Rifled guns do more work than smoothbores because not only do they impart a forward velocity on the projectile, they also introduce a rotational velocity to it. The weight of projectiles in a rifled gun also tends to be greater than that of a smoothbore gun of the same caliber. For example, an 8-inch rifled cannon of that era threw a projectile of weight 180 lbs., whereas the standard load for a 8-inch smooth bore cannon was a 68 lbs. ball.

For larger cannon, a powder designated as "Large Grain" or L.G. was used, until the advent of rifled cannon, at which point a powder called R.L.G (Rifled Large Grain) was introduced. This powder worked well for cannon of smaller caliber, but when guns of 7 inches and larger calibers were introduced, it was found advisable to use a slower burning powder than R.L.G, at which point, Pebble powders (P and P²) were introduced. These were larger grain powders of cubical-shaped grains. P powder grains were about 5/8 inch per side and P² powder grains were 1.5 inch cubes. We will study the manufacture of these powders in a later post.

For small arms, a more rapidly burning powder is required, and therefore these are much smaller grains on average than the ones above. In England, there were four grades of powder produced for small arms:

1. Fine Grain (F.G.) powder to be used by smoothbore firearms (e.g.) the Brown Bess musket. This powder was also used for the charge of 7 pounder muzzle loading cannon and for the bursting charge of shrapnel shells.
2. Rifle Fine Grain (R.F.G.) powder, to be used by most rifled small arms, except the Martini-Henry rifle and pistols.
3. Rifle Fine Grain 2 (R.F.G.²) powder, to be used by the Martini-Henry cartridge.
4. Pistol powder, to be used by pistols and revolvers such as the Colt Single Action revolver and the Deane-Adams revolvers. This is a quick burning powder and is suitable for shorter barrels, where a slower burning powder would not finish burning within the barrel completely. Since it is a very quick burning powder, it was also used for shrapnel shells.

These powders were classified based on grain size and density and were separated by passing the grains of powder through sieves. Sieves are designated according to the number of divisions per linear inch. Therefore, a 4-mesh sieve has 16 holes per square inch, an 8-mesh sieve has 64 holes per square inch and so on. R.F.G. powder should pass through a 12-mesh sieve, but not through a 20-mesh sieve, and have a density of about 1.6. R.F.G.² powder should also pass through a 12-mesh sieve, but not through a 20-mesh sieve, however the density is higher than R.F.G. powder at 1.72. F.G. powder should pass through a 16-mesh, but not through a 36-mesh, while pistol powder should pass through a 44-mesh, but not a 72-mesh. 

In addition to these powders designated for service small arms, there were also powders classed as "Blank powders", used for training purposes. As with the above powders, these were also made in different grain sizes, (e.g. Blank R.L.G., Blank R.F.G., Blank F.G. and so on). These were made from recycled gunpowder from old shells and broken ammunition boxes and only used for firing salutes and training rounds, where the full power of ammunition was not considered critical. 

The following images show the markings of barrels containing different types of powder:

The above image shows a facsimile of a barrel containing P-grade powder (i.e. Pebble powder). The markings tell us the name of the manufacturer ("Waltham Abbey"), the weight (125 lbs.), the type of powder (P, printed in red paint), the manufacturing date and lot number. The 5th line in the image is also interesting, because it tells us the brand of powder (No. 33), the total number of barrels in this brand (56) and the number of this barrel in the brand (24). All this sort of information is put on a barrel containing newly manufactured powder.

In the above three barrels, the topmost one (No. 2) is a returned powder, which was examined on May 20th 1869 and determined to be still suitable for service. The grade of this powder is Large Grain (L.G.) and the letters L.G. are marked in red. The middle barrel (No. 3) is also a returned powder, which was examined, was re-dusted and repaired for service. It is a Rifle Large Grain (RLG) powder and like the one above it, the letters RLG are painted in red. The date of re-dusting is marked as well. The bottom barrel (No. 4) is different from the other two, as it contains Large Grain Blank powder, intended for military exercises and firing blanks. This is made from powder that was extracted from broken cartridges and old cannon shells and returned powders which were found to be too dusty or broken in the grain, to be used in active service.

These barrels were shipped to filling stations where cartridges, shells etc. were manufactured. To enable tracing where a cartridge or shell was filled, each station with a lab had its own unique monogram, as the illustration below shows:

Black Powder - IV: Powder Grain Sizes

In our last post, we saw that the size of the black powder grains are a significant factor in the rate of combustion of the powder and therefore, the pressure curve as well. In today's post, we will look at how powder grain sizes are classified in the US.

Two different grades of black powder. Click on the image to enlarge.

The above image shows two cans of black powder of different grain sizes. Notice that on the top of the can on the left, we see the letters "FFg" and for the can on the right, we see the letters "FFFFg". Modern black powder purchased in the US since about the late 19th century, has been labeled with a combination of the letters F and g, for example Fg, FFg, FFFg etc. These indicate different grain sizes of powder and we'll see what this all means in a minute. The same grade is sometimes referred to by different names. For instance: "FFFg" grade is sometimes referred to as "3Fg", "3F", "FFF" etc.

The last letter of the black powder name indicates the grade of powder. Usually, for firearms applications, this last letter is always 'g'. But this is not the only grade of powder: there are two grades in use:

1. "A" or "blasting grade" powder - the preferred powder of choice for fireworks manufacture.
2. "g" or "sporting grade" powder - preferred for firearms use.

The primary difference between the 'A' and 'g' grades is in the manufacturing process. Both are manufactured in the same way initially, but at the end, the 'g' grade powders are polished in a tumbler with a tiny amount of graphite, to polish the grains and make them flow easily. The 'A' grade powders are not usually tumbled, and if they are tumbled, it is just for a short amount of time to remove any sharp edges. For purchasing the A-grade powder, the user will need to have a BATFE (Bureau of Alcohol, Tobacco, Firearms and Explosives) license and a BATFE-legal magazine to store the powder. Usually that is why it is not commonly seen in sporting goods stores and such. The g-grade is not subject to the same restrictions and is therefore available in gun stores and online shops (only need a BATFE license if purchasing more than 50 lbs. of g-grade powder). Notice that the two cans of black powder in the image above both end with the letter 'g' (One is labeled "FFg" and the other, "FFFFg"), which shows that these are intended mainly for firearms use.

Now on to the mystery behind the letter 'F'. The letter 'F' stands for "Fine" and dates back to the time when the grains were designated F or C (for "coarse" grains). The number of times the letter F occurs in the powder grade shows the average size of the powder grains. The more times the letter F occurs in the name, the smaller the grains. What this means is that the size of "FFFg" grains are smaller than "FFg" grains, and "FFFFg" is even smaller than these two. When black powder is manufactured, the grains are sorted through sieves of standard sizes and classified that way.

Powder Grade	Mesh Size	Average Size in mm.
Whaling	4 mesh	4.750 mm. (0.187 in.)
Cannon	6 mesh	3.35 mm. (0.132 in.)
Saluting (A-1)	10 mesh	2.0 mm. (0.079 in.)
Fg	12 mesh	1.7 mm. (0.0661 in.)
FFg	16 mesh	1.18 mm. (0.0469 in.)
FFFg	20 mesh	0.85 mm. (0.0331 in.)
FFFFg	40 mesh	0.47 mm.
FFFFFg	75 mesh	0.149 mm.

Note that the first 3 grades are intended for use with cannon. The A-1 grade is generally used for artillery blanks used for firing gun salutes. Fg is made for using in large bore rifles and shotguns (8-gauge and larger). FFg powder is used for historical small arms such as muskets, fusils, rifles and large pistols. FFFg powder is for smaller caliber rifles (below .45 caliber), pistols, cap-and-ball revolvers, derringers etc. FFFFg and FFFFFg are mostly used as priming powder for flintlocks. In the image above, the two grades of powder were intended to be used in a historical re-enactment and the FFg powder was meant for the main powder charge of a flintlock rifle, while the FFFFg powder was intended to be used in the pan of the flintlock as a priming powder.

Similarly, the A-grade powders are classified into various grain size ranges (FA, FFA, FFFA, FFFFA, FFFFFA, FFFFFFA, FFFFFFFA, Meal-D and Meal-F (Meal Fine) and Meal XF (Meal Extra-Fine)). However, since these A-grade powders are intended for fireworks and quarries, we will not study them here.

In our next post, we will study the grain size classifications that were used in the UK in the 19th century.

Black Powder - III

In our last post, we studied some of the physical and mechanical properties of gunpowder, information which will come in handy when we study manufacturing methods in some detail. In today's post, we will look at factors that influence the rate of combustion of black powder.

As we saw in the first post of our black powder series, the ratio of saltpeter, sulfur and charcoal in gunpowders varied at different times and in different countries, but by the 19th century, many people had generally settled to using the ratio of 75% saltpeter, 10% sulfur and 15% charcoal. However, powders made by different manufacturers had different pressures and combustion properties even when they were using the same ratio of the ingredients. We aren't even talking about manufacturers from different countries, they could be manufacturers in the same country or even different powders from a single manufacturer. Clearly there must be some other factors that explain why this happens. That is what we will study about in today's post.

The action of black powder depends not only on the composition of its ingredients, but also the size of the grains, shape of the grains and the density of the grains among other things.There are other factors that influence the rate of burning, but these three are the most important. The reason is because black powder is surface-burning. Smaller grains of gunpowder will have more surface area exposed to ignition than a larger grain of the same weight, therefore smaller grain powder will burn faster than the larger grained type. However, if the powder is packed too densely, the flame cannot easily spread from grain to grain, than the same weight of powder packed in a less compact manner. Therefore, very small grain mealed powder and very large grain powder are both slower burning. The shape of the grain also will affect the burn rate, because of the surface area exposed to ignition. Shapes like cubes or spheres offer less surface area than irregular shaped grains of the same mass, therefore they burn slower. This is why laminated or flaky powders burn much faster than normal and diamond shaped grains burn more rapidly than rounded grains.

As a general rule, the larger the grain, the less violent will be the action of gunpowder (i.e.) its combustion will be more gradual. On the other hand, smaller grain powders also cause pellets to scatter much more rapidly than larger grain powders because a smaller grain powder expends all its force before the shot pellets reach the muzzle, whereas a larger grain powder causes the shot pellets to increase their velocity right up to the muzzle of the gun. Therefore, powder designed for weapons with shorter barrels, such as revolvers and pistols, must be of smaller grain, so that they can finish burning before the powder leaves the barrel. Similarly, powders meant for rifled guns are generally a larger grain than those intended for smooth bores, as a more gradual action is required to avoid putting too much strain on the gun barrel.

Since the same manufacturer often makes black powder of different grain shapes, densities and sizes for different types of guns, therefore the shooting qualities of black powder will vary accordingly. We will look at some powders from the 19th century:

Samples of different powders made by Britsh manufacturers.

Click on the image to enlarge. Public domain image.

The above image shows various black powders made in the 19th century by two large British manufacturers Curtis & Harvey and Pigou, Wilks & Laurence. As you can see, the "Revolver" powder is made of very small grains and designed to be fast burning, while Curtis & Harvey's "Col. Hawker's Duck Powder" and Pigou's "Special Punt Powder" are larger grained and designed to be used by very large bore punt guns. Similarly, Diamond #4 and Alliance #4 were generally used for hunting with shotguns, while #6, Rifle, and Martini-Henry powders were designed for rifles. Other large powder manufacturers in England included the E.C. Powder Company, Schultze Gunpowder Company, Kynoch Ltd., Hall, Coopal, Dittmar etc.

Powders made in other countries also varied in grain size, shape and density:

Black powders from different countries.

Click on the image to enlarge. Public domain image.

The above image shows some sample powders made in different countries. Of course, this is only a very small sample. For instance, in the United States in the late 19th century, there were various powder manufacturers, each making multiple types of powder for different applications: DuPont, Hazard Powder Company, Laflin & Rand, Hercules etc.

Various types of black powder made by DuPont

Various types of black powder made by Laflin & Rand.

Images courtesy of the Haglin Museum and Library

Incidentally, the reason why many of Laflin & Rand's black powder offerings were sold under the "Orange" brand name (e.g. Orange Ducking Powder, Orange Rifle Powder, Orange Lightning, Orange Extra Sporting etc.) is because their original production plant was named "Orange Mills" and happened to be located in Orange County, New York.

The quality of charcoal is also a significant factor in the burning rate of the black powder. If the charcoal is improperly charred, then the oxygen and hydrogen retained in it cause it to burn more rapidly than if it is reduced to a pure carbon. The source of wood for the charcoal is also a factor. Experiments conducted in the 19th century showed that there were significant differences in the amount of gas produced by charcoal made from different types of wood. For instance, dogwood charcoal was found to yield about 25% more gas than the same weight of charcoal made from fir, chestnut or hazel trees and 17% more gas than charcoal made from willow. This is why dogwood was preferred for black powder intended for pistols and rifles, while willow charcoal was preferred for making powder for cannons.

In our next post, we will study more into the classification of grain sizes and shapes.