As you can see in the transparent view of the lock, there are many moving parts, so regular cleaning and lubrication is essential in order to minimize friction and prevent rust and wear.
Even under the best of conditions, and with the most meticulous care, flintlock weapons misfired about one out of seven times. Rain, freezing temperatures, wind, high humidity, a worn part, a bit of rust, or a loose screw could reduce reliability to a very low margin. On the morning of September 16, 1805, Clark's gun misfired seven times in succession as he tried to shoot a deer. That may have been because, as he soon discovered, the flint was loose, but also, snow was falling, and the lock could have been wet.
Army regulations, as well as common sense, required every soldier to carry a plug for the end of the gun barrel to keep out rain, snow, mud, and dirt. A hunter closing in for the kill with his rifle loaded and ready to fire had to remember to remove the plug before firing.
Back at Travelers' Rest in early July 1806, Clark noted that two of the rifles had burst near the muzzle. Either a couple of men forgot to remove their barrel plugs, or else they failed to use them at all and got mud or other debris in their barrels. In either case the mistake was inexcusable.
Another essential accessory for every soldier or hunter was a piece of leather to cover the lock in wet or snowy conditions. Often cut from the knee of a cow, and thus pre-shaped to suit the purpose, it was called—what else?—a "cow's knee." On a rainy day in June of 1805 Joseph Fields nearly yielded his life to a grizzly bear because his gun was too wet to fire. Either Fields was uncharacteristically careless, or else the safeguards weren't failsafe.
Despite numerous "improvements" in firearm manufacture since the time of Lewis and Clark, the same old problems have continued to plague soldiers periodically. In Vietnam the new and purportedly self-cleaning M16 rifles instead quickly jammed with hardened carbon deposits and became useless. The whole thing led to a Congressional Inquiry. The Model 1803 Harpers Ferry flintlock rifle might have been more reliable than the M16.
- Carl P. Russell, Firearms, Traps, and Tools of the Mountain Men (New York: Alfred A. Knopf, 1967), 37-43.
- George Markham, Guns of the Elite: Special Forces Firearms, 1940 to the Present (London: Arms and Armour Press, 1987), 178-179.