Hello, I saw that you posted An axe/matchlock musket combination weapon. And I can't see this combination useful in my opinion- as a fire arm the axe is heavy and disturbing the capper of the weapon which will ruin the aiming, as an axe it's not useful anyway because of the lenge of the fire arm and the heavy lift that it will include, I'm not sure but I wanted to ask if any armies actually used this weapons as a primary weapon?
Most combo weapons were more novelty items than practical combat weapons. But there are some rare instance that such weapons were used. In the 15th century the Landsknects (Swiss and German mercenaries) were noted for using axe/gun and axe/mace combo weapons.
King Henry VIII owned a mace which had three concealed gun barrels in it. He often carried it with him for protection.
During the Napoleonic Wars Horatio Nelson carried a sword pistol.