WADR, I think your brother's safety education is lacking. When I was packing a percussion rifle, and when I pack my DB percussion shotgun, I always have the hammers at half cock, and I always have a hand either behind the hammer(s), or with the heel and little finger of the hand over the top of the hammers, blocking the hammer spurs from brush with my hand and arm as I go through brush. I Do not ever carry a percussion or flintlock without protecting that exposed hammer from being "grabbed" by brush.
With a flintlock, you can use a leather hammer stall that fits over the frizzen, and prevents an errant hammer drop from creating any sparks. With percussion guns, You can make a hammer stall out of certain pistol cartridge casings, that will fit over the nipple and percussion cap, but prevent the hammer from falling and striking the cap. The casing is tied to the trigger guard so that it can be simply removed and dropped and it stays with the gun to be put to use again. I kow a man who swore by using one of those rubber, rectangular shaped pencil erasers as a hammer stall/safety on his percussion rifle. He drilled a 1/4" hole in one end of the eraser, for this string used to tie it to his trigger guard. The other end was place over the capped nipple, and in front of the hammer. The eraser was so thick, the hammer did not go into its half cock notch on that gun. If the hammer spur caught a branch that pulled the hammer back enough, the weight of that eraser would be enough to make it fall, and he could easily feel the heavy weight of the eraser begin swinging below the trigger guard, and know what happened. The hammer had to go back into the full cock notch for the eraser to come off the nipple and cap.
I prefer to not rely on mechanical safeties of any kind, and keep my hand on my lock any time I am moving. "The only safety on a gun that works is YOU!" ( My Eleventh Commandment of Gun Safety.)
