Even though it's named after another state, my vote would go to the Kentucky Long Rifle. It was the most effective weapon used to defend the Alamo, probably second only to the cannon. Actually, the cannon might be pretty good too.
“He grouped his last five shots right in the center of the bull’s-eye. Then I showed him my technique of scattering shots randomly around the target because, as I explained, you never know which way the deer might jump just as you pull the trigger.”