If the granules are diamond shaped it is ever better. A quote I found;
Curtis's & Harvey was my great,great grandfather's Company. There is no great secrecy about the ingredients, the superiority was down to meticulousness, purity of materials, and a deep understanding of the production and nature of the charcoal combined with a long incorporation time under the edge runners. Modern production costs would make powder of this quality prohibitively expensive even if anyone could be found who could replicate the charcoal.
Back in the 1950s, I used lots of this powder in the superior "Diamond Grain" series, manufactured around about a hundred years ago, and I have never yet seen anything to come near it for lack of fouling and relative absence of smoke compared to modern powders. We shall never see its like again. Of course, they also made every other grade of black powder and blasting powders. When Bickford invented Safety Fuse around 1830/40, C&H bought him out very quickly.
You must remember that when this was the only propellant, no expense was spared and only the finest was acceptable to the likes of Sir Henry Halford, Metford, Lord Bury, and the grandees of the National Rifle Association, not to mention the even grander aristocracy of the grouse moors. This attention to detail, combined with financial acumen, meant that C&H from its inception in 1820 when C.B.Curtis's father, Sir William Curtis, purchased the old failing partnership of Harvey & Grueber at Hounslow (to the west of London) by the end of the 19th Century had become the sole commercial manufacturers of black powder in the entire British Empire. They had bought out every other maker. The end of the Company's independence was brought about by World War One after which every commercial manufacturer of explosives and ammunition of all kinds amalgamated into Explosives Trades Limited which morphed into Imperial Chemical Industries Limited (ICI) of which C&H were a component Company.
