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The first American attempts at interchangeability took place during the beginning decades of the 19th century. At that time, the government supplied a pattern or an example of the arm. However, interchangeability failed to be established, because the patterns wore down and replacing them were costly.1 One of the first American inventors to introduce interchangeability into the manufacturing world was Eli Whitney after the War of 1812.2a However, his system and others closely following his were not extremely successful. John Harris Hall, inventor of the Hall carbine and assistant armor at Harper’s Ferry, and Samuel Colt, known for his revolvers and revolving rifle, more-successfully led the way to interchangeable parts.3 However, Colt would not fully achieve interchangeability of its revolver parts either, because the guns were still hand fitted together at the end of production.4 As seen through both Colt and Whitney’s operations, mechanizing the production process did not mean that the parts will be truly interchangeable during the Civil War.5

According to Historian Donald R. Hoke, "nineteenth century manufacturers never thought of interchangeability as an absolute and interchangeability meant different things to different manufacturers."6 Money, power supply, and the capability to use the machine tools to their full ability were all factors that played into a company’s manufacture of interchangeable parts. While some factories reached interchangeability of arms’ parts, other struggled with the task and could only really make uniform parts.


when two or more identical parts are able to replace each other


Used to measure if manufactured parts were uniform, more specifically interchangeable; three types of gauges were used: inspection gauges, master gauges (used to check the inspection gauges), and production gauges.32 

John Brown's Raid on Harper's Ferry

Oct. 16, 1859. Abolitionist John Brown and his followers, armed with Sharps Carbines, attempted and failed to take over Harper's Ferry Armory, obtain weapons there, and inspire a slave insurrection.

"For it was in the realm of arms manufacture that the first attempts to attain interchangeability of parts had been made at the turn of the nineteenth century."

--Otto Mayr
and Robert C. Post,

Yankee Enterprise:  
The Rise of the American System of Manufacturers,
page xiv


the ideal form of the gun being manufactured; all those produced were imperfect33

Simeon North was the first inventor that successfully used interchangeable parts in a firearm.b In 1799, North created machines for his contract with the government for pistols. After he re-outfitted his factory with new machines, he started to deliver the government's order in 1815.7 His machines promoted the possibility of interchangeable parts as a reality to those that visited his factory, including those men from Harper's Ferry and Springfield.

Before the Civil War, Harper’s Ferry and Springfield Armories worked towards interchangeability2 with varied degrees of success. However, after John Brown’s raid on Harper’s Ferry, that armory was closed, and its guns were distributed to the South at the outbreak of the war. In the North during the Civil War, the Springfield Armory led the process of standardizing its rifle parts with its contractors through supplying the private firms with the part patterns, gauges, and gun models as well as with advice.8

Interchangeability and the Civil War

The prospect of uniform parts also inspired the carbine manufacturers to create interchangeable parts within their own gun designs. All of the contractors’ subcontractors created the patterned parts that fit together into the larger carbine. In order to acquire interchangeable parts, manufacturers were inspired to create or obtain machines that helped produce that goal. Multiple manufacturers could have created the same parts required for large orders or contracts. That process of mass production armed the troops, and provided them with new rifled muskets and carbines by mid-1863.
9 According to Historian Felicia Johnson Deyrup, “the invention of certain highly specialized machines and the application of important mechanical principles are directly attributable to small arms manufacture.”10 In fact, inventors from the machine tool industry and the small arms industry, such as Christopher Spencer, patented items in each industry. The drive for interchangeable parts during the Civil War drew the industries even closer together as the factories struggled to meet government contracts. Due to interchangeability the two industries would be forever linked.

With the advancements of machine tools, full interchangeability for carbine parts became more and more possible. Those uniform parts were advocated by the government who promoted standardization within its armories as well as through its inspections of private contractors' products. Because subcontractors and contractors began to make the same parts as other firms during the war, "only with the Civil War did uniformity among products from different plants became widespread."11 However, due to the experimental state of the machines and fluctuations in material and labor, standardization could not fully be accomplished.12

The method of creating interchangeable parts was almost, but not entirely, perfected during the Civil War. That was, in part, due to Chief of Ordnance Ripley’s advocacy for interchangeable parts that forced contractors to follow already established patterns and gages.13 The interchangeability of parts, a standard that needed to be met for government contracts, was one of the propelling forces for private firms to obtain machines that were capable of creating those standard arms. Another incentive was that interchangeability allowed production to be simplified and more easily isolated machines’ problems when production errors occurred, saving money in the long run.14 Although machines used for interchangeability caused production costs to increase significantly, the machines for interchangeable parts decreased the labor cost.15

Not only individual inventors, but also factories, such as Robbins & Lawrence Company, became known for their interchangeable parts. Robbins & Lawrence Company created machine tools as well as Sharps carbines.16 Those carbines were known for their high-quality and reliable, interchangeable parts due to their manufacturer's use of precision machine tools.17 The Robbins & Lawrence machinists worked for years on tools to make the parts almost truly interchangeable.  That process can be seen in the evolution of the Sharps that the company, or its top men, was in charge of manufacturing:  In the 1851 through 1855 models, the parts were mostly interchangeable, and then in the 1859 model and after, the carbines’ parts were almost entirely interchangeable.18

Interchangeable parts applied to more than just the pieces of the same type or make of gun or between two manufacturers.19 Certain parts could sometimes be applied to different makes of guns from different manufacturers. For example, because of Richard Lawrence’s (of Robbins & Lawrence) friendship with Christopher Spencer, who patented the Spencer Repeating Rifles and Carbines, some of the gun parts for each of these guns were interchangeable. Those parts included the tumbler, bridles, mainsprings, and mainspring swivels (which were pieces of the percussion locks). Those interchangeable parts were included in the 1859 Sharps Model as well as the models after 1859 and in the 1860 and 1865 Models of the Spencer.20

Along with improving mass production, interchangeable parts’ helpfulness played a role in the Civil War's conflicts and battles. Before interchangeable parts, when guns broke they had to be sent back to the armory to be fixed.21 With the new uniform parts, men could fix their guns relatively quickly, and they were able to properly fight again due to having a working gun. In this way, the military supported interchangeable parts.22 For that reason, the Ordnance Department was willing to pay for the more expensive manufacturing process and its products featuring uniform and interchangeable parts.

Checking Part Interchangeability

In order for the parts to be considered interchangeable, all of the carbines' pieces had to be able to be exchanged for replacement parts. By formulating and perfecting an elaborate gauge system and other machine parts, the manufacturers were able to intricately and precisely create small gun pieces and their identical copies.
23 Because each part of an arm used a separate set of “jigs and fixtures” specialized to produce the same pattern over and over, the manufacturers needed a relatively easy way to check each system to ensure that they continually created interchangeable parts. A system of gauges, called “go or no-go” gauges, was created to measure firearm parts. Those gauges were metal pieces with holes or rectangular chunks cut out of them. A part was then either lined up with or fit into a corresponding gauge to determine if it met the government’s requirements.24 John Hall, who had achieved interchangeable parts by 1826c, used 63 gauges to measure his parts.25 During the Civil War Springfield Armory used at least 150 gauges to measure uniformity.26

a According to Martin Rywell in The Gun That Shaped American Destiny, during a 1798 government contract for muskets Eli Whitney started designing and creating machines for interchangeable parts.27
b According to Historians Otto Mayr and Robert Post, Hall established interchangeable parts eight years before North.
28 According to Historian Merritt Monroe Smith, North did not achieve the level of interchangeability that Hall had by 1827.29 North manufactured rifles that some of the pieces interchanged with the rifles made at Harper's Ferry, where Hall was superintendent, in 1827. 30
c Historian Donald Hoke seems to suggest that Hall achieved interchangeable parts by 1824 when government officials toured his factory.
d When referring the “type” of gun, this website means if it is a pistol, carbine, rifle, or smoothbore, percussion, etc. When referring to “make” or “brand,” it means the name given to the gun, such as Sharps, Spencer, or Colt.



1 Felicia Johnson Deyrup, Arms Makers of the Connecticut Valley: A Regional Study of the Economic Development of the Small Arms Industry, 1798-1870 (George Banta Publishing Company: Menasha, Wisconsin, 1948), 56.
2 Deyrup, Arms Makers of the Connecticut Valley, 11.
3 Joseph G. Bilby, A Revolution in Arms:  A History of the First Repeating Rifles (Yardley, Pennsylvania: Westholme Publishing, LLC, 2006), 32.
4 Otto Mayr and Robert C. Post, eds. Yankee Enterprise: The Rise of the American System of Manufacturers (Washington, D. C.:  Smithsonian Institution Press, 1981), 3-4.
5 Mayr and Post, Yankee Enterprise, 4.
6 Donald R. Hoke, Ingenious Yankees:  The Rise of the American System of Manufacturers in the Private Sector (New York:  Columbia University Press, 1990), 26.
7 Edwin A. Battison, Muskets to Mass Production:  The Men & The Times that shaped American Manufacturing (Windsor, Vermont: The American Precision Museum, 1976), 10.
8 Paul A. C. Koistinen, Beating Plowshares Into Swords:  The Political Economy of American Warfare, 1606¬1865 (Lawrence, Kansas: University Press of Kansas, 1996), 165.
9 Carrie Brown, “Guns for Billy Yank: The Armory in Windsor Meets the Challenge of Civil War,” Vermont History 79, no. 2 (Summer/Fall 2011): 143.
10 Deyrup, Arms Makers of the Connecticut Valley, 13.
11 Deyrup, Arms Makers of the Connecticut Valley, 194.
12 Deyrup, Arms Makers of the Connecticut Valley, 195.
13 Carl L. Davis, Arming the Union:  Small Arms in the Civil War (Port Washington, New York: Kennikat Press, Inc., 1973), 74; Koistinen, Beating Plowshares Into Swords, 165.
14 Mayer and Post, Yankee Enterprise, 58.
15 Donald R. Hoke, Ingenious Yankees:  The Rise of the American System of Manufacturers in the Private Sector (New York:  Columbia University Press, 1990), 4.
16 Winston O. Smith, The Sharps Rifle: Its History, Development and Operation (New York: William Morrow & Company, 1943), 4.
17 Winston Smith, The Sharps Rifle, 27.
18 Winston Smith, The Sharps Rifle, 53.
19 Mayr and Post, Yankee Enterprise, 112.
20 Winston Smith, The Sharps Rifle, 55.
21 Winston Smith, The Sharps Rifle, 3-4; Mayer and Post, Yankee Enterprise, 3.
22 Brooke Hindle and Steven Lubar, Engines of Change: the American Industrial Revolution, 1790 – 1860 (Washington, D.C.: Smithsonian Institution Press, 1986), 218.
23 Deyrup, Arms Makers of the Connecticut Valley, 13, 145; Hindle and Lubar, Engines of Change, 30-31.
24 Hindle and Lubar, Engines of Change, 230-231.
25 Mayr and Post, Yankee Enterprise, 76.
26 Mayr and Post, Yankee Enterprise, note 34 on p. 99.
27 Martin Rywell, The Gun That Shaped American Destiny (Harriman, Tennessee:  Pioneer Press, 1957), 4.
28 Mayr and Post, Yankee Enterprise, 76-77.
29 Merritt Roe Smith, Harper’s Ferry Armory and the New Technology:  The Challenge of Change (Ithaca: Cornell University Press, 1977), 207.
30 Merritt Smith, Harper’s Ferry Armory and the New Technology, 212.
31 Hoke, Ingenious Yankees, 200.

32 Mayr and Post, Yankee Enterprise, 129.

33 Mayr and Post, Yankee Enterprise, 128.

Uniform vs. Interchangeable

Uniform parts were very similar parts, but could not be interchangeable, such as Colt’s revolver’s pieces.


Harpers Ferry c. 1865-1866


According to David Miller, Associate Curator in Armed Forces History at the Smithsonian, "The U.S. Model 1841 Percussion Rifle is known as the Mississippi Rifle, but has never been called a “Springfield” rifle.  It was produced at Harpers Ferry.  The gauges were used to inspect Model 1841 rifles produced by contractors such as Remington, Robbins, Kendall & Lawrence, and Eli Whitney, Jr."

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