The small bore rifles also generate the highest pressures, just using FFFg powder charges of 20-40 grains. You should NEVER USE a finer powder in the barrel as a main charge. That includes, FFFFg priming powder, and anything finer, including fuse powders, and flash powders for old time cameras, that are rated, 7Fg and 10 Fg. These would generate excessive pressures for any gun and could prove dangerous to the shooter. Remember, unlike a modern cartridge gun, where you have the powder encased in a sturdy brass casing, which has a tensile strength capable of taking 55,000 fpe by its self, and is then surrounded by modern steel barrels and breechblocks that can also take 75,000 fpe and more, that replica percussion or flint rifle, even made of modern steels, still has a hole from the powder charge to the outside of the barrel located only a few inches from your hands and face when you pull the trigger. I saw a nipple and flash cup disappear out of the back of my brother's rifle when he fired a relatively modest load of FFFg powder in his 40 cal. percussion rifle years ago. The threads in the drum for the nipple were oversized, and my brother did not know it until the mishap occurred. The pressures generated by the .36, and .32 caliber rifles is a lot higher. No one was hurt in my brother's " Accident" but the event reminded us that these are real guns, firing real explosive compounds, that generate real pressures. While the pressure decreases rapidly, for a part of a second, the barrel, breechplug, drum, nipple, or vent are all put under a large amount of strain. Don't be fooling around with these odd powders that were never intended to be used in a gun! YOu could injure yourself, or others, needlessly, by your negligence, damage a fine firearm, and give this sport a bad name for no reason that you will ever be able to sell to a Judge.
