Here is a bit from the research I mentioned earlier that we were given authorization to share:
"The new powder for revolvers was at first called "Cartridge Powder", due to its initial use for revolver combustible cartridges. Using "Cartridge Powder", a charge of only 25 grains would move a 220-grain conical close to velocities requiring 40 grains of rifle-grade gunpowder in the Colt Dragoon. The use of a smaller charge of gunpowder for the same performance, also gave the advantage of less fouling, so that a revolver could be fired more often until disabled by fouling buildup.
In 1855, at the time Colt's Cartridge Works began operation, Samuel Colt and Colonel Augustus Hazard were well acquainted. Colonel Hazard was the owner of Hazard Powder Company, so it is no coincidence that Colt's Cartridge packets are all marked "Made with Hazard's Powder", as shown on the Dragoon combustible packet illustrated in Photo "A". It seems likely and probable, that Hazard Powder Company was the originator of a "Cartridge Powder" formulated for best performance in revolvers. The early 1860's packet of D. C. Sage .44 Army Combustibles illustrated in Photo "B" are marked "Made of Hazard's First Quality Cartridge Powder".
In AMERICAN MANUFACTURERS of COMBUSTIBLE AMMUNITION (AMCA), author Terry White discovered the gunpowder type "Number 1 Pistol Powder" in the records of H. W. Mason. Both Hazard Powder and American Powder Company supplied this gunpowder type to Mason's combustible cartridge shop. Illustrated in Photo "C" is a .44 Army combustible packet made by H. W. Mason marked "Made with Hazard's Powder". Hazard's "First Quality Cartridge Powder" and "Number 1 Pistol Powder" are trade names for the generic powder type clearly identified as "Revolver Powder" in "THE GUN" (TG) by author W. W. Greener.
Knowing that a special "Revolver Powder" existed for percussion revolvers, and even knowing all the names for that special powder still does not describe what it is and how it differs from the familiar FFFg and FFg powders, for those of us in the 21st Century rediscovering the percussion revolver. Lucky for us, however, in the last half of the 19th Century, Major John Symington at the Allegheny Arsenal near Pittsburgh, Pennsylvania, dissected and test fired some of Colt's revolver combustibles and wrote a very clear description of "Revolver Powder". W.W. Greener went even further, and provided an illustration of gunpowder granulations in his book "THE GUN"! Pictured among those granulations is a grade marked "Revolver Powder" and it precisely matches the written description of Major Symington.
Major Symington's written description of the Hazard Powder used in Colt's combustible cartridges is quoted from pages 5 and 7 of "ROUND BALL to RIMFIRE, PART 3" (RBRF3), and is from reports written to Chief of Ordnance Colonel Henry K. Craig in June 1860.
Major Symington describes Colt's combustibles as, "The larger bullet was .456 in. diameter, and weighed 230 grains; the charge of powder weighed 20 grains. The small bullet was .383 in. diameter, and weighed 120 grains; the powder charge weighed 12 grains. The powder of both sizes of cartridges was of very fine grain called sporting powder, manufactured specially for these arms...."
After test firing Colt's combustibles, Major Symington reported, "The severity of shock [recoil] was due to the rapid combustion of such fine grained powder, particularly noted in Colt's cartridges, the powder of which is of special make.....'.
On page 552 of "THE GUN" (TG), the powder granulation illustration (Photo "D") shows "Revolver Powder" to be very fine grained exactly as Major Symington described the Hazard gunpowder used in Colt's combustible cartridges. The Hazard Powder described by Major Symington, and the "Revolver Powder" illustrated in THE GUN, is practically identical to FFFFg granulation today.
Original Colt revolver nipples are illustrated in Photo E. In Photo F, modern Uberti revolver nipples are pictured. Notice how tiny the flash holes are on the original Colt nipples compared to the much larger flash holes of the modern Uberti nipples. Very fine-grained gunpowder can be loaded without dribbling through the tiny flash holes of the original Colt nipples. The much larger diameter flash hole of the modern Uberti nipples allows very fine-grained gunpowder to dribble through the nipple. This dribble through of powder creates a danger of chain-fire, which is one of the two dangers of using FFFFg in a percussion revolver that will be addressed later in this article.
The charge of 20 grains under a 230-grain bullet sounds very underpowered to those of us accustomed to firing low-performance modern-made gunpowder in the years of the 1970's through 1990's. However, the low powder charge described by Major Symington apparently generated excellent performance, because the Major commented on the sharp shock [recoil] of the Colt combustible cartridges in particular! Sharper recoil equals higher velocity, as stated by Newton's Third Law of Motion, where every action is followed by an equal and opposite reaction.
In the section on "Black Powder" in UNDERSTANDING FIREARMS BALLISTICS (UFB), author Robert A. Rinker's clear explanation of gunpowder characteristics, clarifies the Hazard Powder Company decision to provide FFFFg sporting-grade gunpowder for revolver use. "Experience and experimentation taught early gunners that particle size controlled the speed of combustion...............FFFFg was the smallest particle with the fastest burn rate and is used mainly in handguns." (UFB, page 23).
With a bit of thought, it becomes clear why the short chambers of a revolver's rotating breech would require a special powder capable of rapid combustion. Obviously, coarse-grained musket and rifle-grade gunpowders designed for use in barrel lengths of 30 inches and longer are not going to perform efficiently in a combustion chamber averaging a bit over an inch in length. With that bit of reasoning in mind, the Hazard Powder Company decision that very fine grain (FFFFg) gunpowder was best suited to the percussion revolver's combustion dynamics makes a lot of sense.
Hazard Powder Company's "Revolver Powder" was a fast-combusting FFFFg made from high performance Sporting-grade gunpowder, providing the most power possible from a given charge of gunpowder! This very potent Hazard "Number 1 Pistol Powder" is precisely the "First Quality Cartridge Powder" Hazard provided to Colt, D.C. Sage, H. W. Mason and other manufacturers of revolver combustible cartridges.
Now, before anyone runs out to buy a can of Swiss Blackpowder FFFFg to stuff in their favorite percussion "smoke wagon", be aware that FFFFg can be VERY DANGEROUS, ESPECIALLY in a revolver, unless you precisely understand the problems unique to FFFFg, that can arise from FFFFg use in a revolver.
Loaded properly with due caution, and with CORRECT charges, FFFFg is perfectly safe, and makes an excellent percussion revolver propellant. Near the end of this article I will detail the dangers that can arise from FFFFg use in a revolver. By understanding the possible dangers that can arise with improper use of FFFFg, the proper and safe use of this very fine grain powder in revolvers will be very clear.
As explained earlier, "Revolver Gunpowder" of the period from 1855 to 1875, was revealed to be sporting-grade gunpowder in FFFFg granulation. Combustible cartridges made by Colt's Cartridge Works used very fine grain sporting-grade gunpowder as documented by Major John Symington in June 1860. Major Symington of the Allegheny Arsenal near Pittsburgh, Pennsylvania, had dissected and test fired Colt's combustibles in .36 and .44 caliber, detailing their construction and performance in his June 1860 report to Chief of Ordnance Colonel Henry T. Craig.
Major Symington did not like Colt's combustible cartridges, because they recoiled sharply when fired, and because Colt's prices were too high. For test purposes, Major Symington constructed revolver combustibles at the Allegheny Arsenal, using tissue paper (similar to gift-wrapping tissue) envelopes and replacing the very fine grain sporting grade gunpowder with fine grain (FFFg) rifle grade powder. He thought the FFFg still generated too much recoil and recommended using musket-grade powder to keep recoil light! It appears that Major Symington was more interested in an easily controlled handgun rather than maximum power."
