I have and have had original flinters that have touch holes bigger than anything we have today, some are from use but most were made larger to use one powder for charging and shooting. In the time of battle one wouldn't have time to fumble around for another horn.
Osborn Russell wrote that most of the mountain men he has encountered carried two horns, (1) was with his shooting bag and (1) was a larger horn used as a storage horn, no mention of a priming horn. Like Pete mentioned the powders available were very poor with only a couple available, one for shooting cannon and a finer powder for hand and shoulder arms. There are many accounts from men like Carson, Medina, Toblin and others that when questioned about their equipment only mention one powder horn and sometimes mention a storage horn, nothing of a priming horn.
Some museums have examples of powders, there is no way from the size of the blasting/cannon powder of working in a sporting arm.
"A" or "blasting grade" powder - the preferred powder of choice for fireworks/cannon and blasting.
"g" or "sporting grade" powder - preferred for firearms use being finer.
__________________________________________________
FIREARMS HISTORY, TECHNOLOGY & DEVELOPMENT
How powder grain sizes are classified in the US.
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.
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.
Note: the first 3 grades are intended for use with cannon. The A-1, A-2 and A-3 grades are 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 historical for 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 later years or found in Europe.
There are two grades of powder 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. (Modern thinking).
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.
______________________________________