Interchangeable parts
Origins of the modern concept

In the late-18th century, French General Jean-Baptiste Vaquette de Gribeauval promoted standardized weapons in what became known as the Système Gribeauval after it was issued as a royal order in 1765. (At the time the system focused on artillery more than on muskets or handguns.) One of the accomplishments of the system was that solid-cast cannons were bored to precise tolerances, which allowed the walls to be thinner than cannons poured with hollow cores. However, because cores were often off-center, the wall thickness determined the size of the bore. Standardized boring made for shorter cannons without sacrificing accuracy and range because of the tighter fit of the shells; it also allowed standardization of the shells.

Before the 18th century, devices such as guns were made one at a time by gunsmiths in a unique manner. If one single component of a firearm needed a replacement, the entire firearm either had to be sent to an expert gunsmith for custom repairs, or discarded and replaced by another firearm. During the 18th and early-19th centuries, the idea of replacing these methods with a system of interchangeable manufacture gradually developed. The development took decades and involved many people.

Gribeauval provided patronage to Honoré Blanc, who attempted to implement the Système Gribeauval at the musket level. By around 1778, Honoré Blanc began producing some of the first firearms with interchangeable flintlock mechanisms, although they were carefully made by craftsmen. Blanc demonstrated in front of a committee of scientists that his muskets could be fitted with flintlock mechanisms picked at random from a pile of parts.

In 1785 muskets with interchangeable locks caught the attention of the United States' Ambassador to France, Thomas Jefferson, through the efforts of Honoré Blanc. Jefferson tried unsuccessfully to persuade Blanc to move to America, then wrote to the American Secretary of War with the idea, and when he returned to the USA he worked to fund its development. President George Washington approved of the concept, and in 1798 Eli Whitney signed a contract to mass-produce 12,000 muskets built under the new system.

Louis de Tousard, who fled the French Revolution, joined the U.S. Corp of Artillerists in 1795 and wrote an influential artillerist's manual that stressed the importance of standardization.
startend:quotation