Pukka black powder (BP) or a smokeless equivalent.

An awkward choice, BP is a must for some competitions, some find the smell and smoke a part of the enjoyment of using it.

Many say the firearms we used were designed to use BP, to some extent this is true. Our modern replicas are made to finer tolerances on modern machines using modern materials certified to be of high quality so they are far safer and perfectly capable of handling the modern smokeless powders. Not I hasten to add powders designed for reloading cartridges.

I say true, a factor to consider is the rifling twist is optimised for BP. Pyrodex is formulated to perform the same as BP (well almost). Triple 7 is an even more modern introduction which burns with slightly more energy (+15%) and seems faster burning.

BP is classed as an explosive, because of this to hold it you need a license and a suitable storage container (more later). You also need authority to transport it and you will not be sold it if you cannot show these two documents.

Smokeless is easier to get (it is far from smokeless), even via mail order. The storage is the same as normal reloading powders, so this is the preferred stuff for many of us.

In use BP is dirty smelly and messy, and good fun. Pryodex is similar though the smell is not quite as rich. Both these powders are corrosive, the residues draw moisture out of the air and being sulfur based they produce an acidic tar that can damage hardware in a matter of hours. A strict cleaning regime is what you will often read about amongst m/l users.

Triple 7 is relatively new and still a bit hard to source in the Uk. It's smell is no where near as nice. It produces about 30% less smoke is slightly hotter and faster burning and because it is sulfur free the residue is considerably if not 100% less corrosive.

There are other powders such as cleanshot but they are hard to source so wont be of interest to newer shooters.