The Modern Era Arrives

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Smokeless rifle powders, Part 1

Most people consider history as wide-spaced major leaps, disregarding the incremental steps between, the reason many shooters think smokeless powder suddenly appeared in the French Lebel rifle in 1886, even though other smokeless powders appeared as early as the 1840’s.

Black powder had already been around for over 500 years, and while it obviously worked, it was inefficient. Only about half burned, limiting velocity and leaving considerable fouling in the bore, but black’s biggest fault was the cloud of white smoke accompanying each shot, obscuring the vision of soldiers and revealing their position to enemies.

The solution turned out to be combining nitric acid with cellulose, the basic building block of plant cells, resulting in what’s called nitrocellulose. The first notable success is usually attributed to Christian Schoenbein, a chemistry professor in Switzerland, in 1846, and used abundant, absorbent cotton fiber. “Guncotton” worked in some firearms, but blew up others—and a number of factories. Wood-based nitrocellulose powders burned a little slower, reducing blow-ups, and by the 1860’s were used in handguns and shotguns, though still proved too fast-burning for rifles.

Practical rifle powders became possible with the development of early plastics made by “gelatinizing” nitrocellulose with solvents such as ether and alcohol. Among the early products were billiard balls and camera film, but another was much slower-burning nitrocellulose powder, eventually resulting in the Poudre B used in 8mm Lebel ammunition, an improved version of powders developed by French chemist Paul Vielle in the early 1880’s.

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Among early extruded powders was Cordite, left uncut in long strands.
This batch is from a .303 British military round, and the Cordite is the
“natural” color of nitrocellulose. Most powders are black due to graphite
added to subdue static electricity.

Squished Competition

However, as told in Philip Sharpe’s Complete Guide to Handloading, a similar powder was patented in 1870 by Austrian Frederick Volkmann, who started producing it commercially. At the time the Austrian government totally controlled powder making, and in a classic example of heavy-handed bureaucracy, closed Volkman’s plant. Otherwise the Austrian army might have been the first armed with smokeless rifles.

In 1888 Alfred Nobel, who’d used nitroglycerin to develop dynamite a dozen years earlier, patented a process using nitroglycerin to help gelatinize nitrocellulose, and his Ballistite became the first “double-based” gun powder. Nitroglycerin increased the amount of energy contained in a given amount of powder, resulting in more velocity.

But so many chemists had already been working on similar powders that after 1886 the armies of many countries almost immediately adopted smokeless cartridges in new rifles. Germany and Austria went smokeless in 1888, and by 1894 more than dozen other countries had as well.

Unfortunately, early powders deteriorated rapidly, blowing up not only firearms but ships and buildings, so stabilizers were added. The first improvement of Poudre B appeared in 1888, and by the late 1890’s most smokeless propellants were far safer. However, they remained relatively sensitive to temperature, especially heat. British sporting cartridges often appeared in two versions, one for the British Isles and other cooler climates, and “tropical” cartridges loaded with a smaller charge for hunting in the hotter parts of the Empire.

Early smokeless powders burned fastest upon ignition, burning slower as the bullet or shot charge moved down the bore. This is called “degressive” burning, but soon it became apparent that a “progressive” rifle powder—burning slowest immediately after ignition, then increasing in rate as the projectile moves down the bore—would result in lower peak pressure and higher velocity. This difference between degressive and progressive powders is why handloaders often disagree about the effect of seating bullet depth. With the degressive powders used in most handguns, pressure increases when bullets are seated deeper, but with progressive powders, pressure decreases with deeper seating. (Or at least it does in most cartridges chambered in shoulder-fired rifles.)

In black powder, burn-rate was controlled by varying granule size. Larger granules have less surface area per granule volume. Fg burns slower than FFFFG because the inside can’t burn until the surface burns. FFFFG granules burn up almost instantly, because they’re basically all surface. Most early smokeless powders were flat flakes, with little variation in surface area, but gelatinized nitrocellulose could be forced through holes in metal, resulting in strands of extruded propellant. Usually the strands were cut into short sections, but British Cordite was left long, resembling uncooked spaghetti.

Eventually chemicals to slow initial burning were added to the surface of powder. These retardant coatings made even smaller granules possible, and smaller granules can be mechanically measured into cartridge cases faster and more accurately, speeding up ammunition production. In the 1930’s Dr. Fred Olsen, working for Olin’s Western Cartridge Company, developed a much quicker method of making even smaller-granuled smokeless rifle powder, by stirring a slurry rapidly until tiny “bubbles” of nitrocellulose formed. Ball Powder (trademarked) could be manufactured far quicker than flake or extruded powders, and flowed easily into cases.

But it also created problems—or recreated them. Most extruded powders were relatively clean-burning, but the high percentage of retardant coating on Ball Powder resulted in noticeably more fouling, both in bores and the mechanisms of gas-operated automatic and semi-automatic firearms. Retardant fouling was also somewhat abrasive, increasing copper fouling in bores.

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Much of the lore of modern handloading comes from surplus World War II powders
sold on the civilian market. Among the most popular was a 20mm cannon powder
Bruce Hodgdon rebranded as H4831 (right), but the latest H4831 (left) represents
the second generation of commercially produced powder.

But it also created problems—or recreated them. Most extruded powders were relatively clean-burning, but the high percentage of retardant coating on Ball Powder resulted in noticeably more fouling, both in bores and the mechanisms of gas-operated automatic and semi-automatic firearms. Retardant fouling was also somewhat abrasive, increasing copper fouling in bores.

Copper alloys had been used for bullet jackets almost immediately after practical smokeless powders appeared, but the preferred early alloy was cupronickel, approximately 3/4 copper and 1/4 nickel. Cupronickel fouling built up so rapidly rifle barrels sometimes split, the reason grooves in 8×57 barrels were deepened a few years after the cartridge’s introduction. In artillery barrels, strips of cupronickel could sometimes be seen hanging from the muzzle.

During World War I it was discovered that adding pieces of lead or tin to artillery powder charges reduced copper fouling considerably. The heat and pressure of burning powder combined them with copper, forming a brittle amalgam blown out by following shots. In 1919 DuPont reduced cupronickel fouling in rifles by incorporating tin in granules of early Improved Military Rifle (IMR) powders, denoted by adding “1/2” to the powder number.

By the1920’s cupronickel was replaced by gilding metal, 90 to 95 percent copper combined with 5 to 10 percent zinc, reducing copper-fouling considerably. But the introduction of Ball Powder in 1933 increased copper-fouling again, so “decoppering agents” were added to military Ball powders.
Ball powder didn’t become popular among handloaders until after World War II, when “war surplus” powder was sold to civilians, and similar or identical powders produced specifically for handloaders. However, post-war powder manufacturers apparently didn’t see copper-fouling as a concern for civilian shooters, who unlike soldiers had plenty of spare time to clean barrels, so most new powders didn’t contain decoppering agents.

Cheap and abundant mil-surp powder was part of a perfect storm of factors creating a post-war boom in handloading. Many ex-soldiers had found they liked to shoot rifles, and handloading was an affordable way to shoot more, whether at “varmints,” edible game, or inanimate targets. Benchrest shooting became very popular, and many books and magazine articles explained how make better rifle ammunition than factory stuff.

Consequently a lot of the lore of rifle handloading appeared during those post-war decades, including firm beliefs about smokeless rifle powders that still exist today, despite continued advancements. We’ll look at those beliefs and how rifle powders have improved since the middle of the 20th century in my next column.

Half of John Barsness’s dozen books are on firearms and shooting. His latest is The Hunter’s Guide to Handloading Smokeless Rifle Cartridges, published in the fall of 2015 by Deep Creek Press. It’s available through www.riflesanrecipes.com, P.O. Box 579, Townsend, MT 59644, (406) 521-0273.

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One thought on “The Modern Era Arrives

  1. Anthony Lewis

    Hi, I just read this article in the print magazine and I’m having a hard time getting my head around the part about pressure decreasing with deeper seating depth with progressive powders. My first thought was a deeper seating depth would alter the pressure curve in that initially, the powder would burn more efficiently and you would see a faster rise to pressure, but with less powder remaining to continue the progressive burn at that point, the pressure would sort of level out and actually result in a lower overall peak pressure. That’s about all I can come up with. Could you explain this phenomenon a bit more? Thanks in advance!

    Reply

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