J-Frame/K-Frame/L-Frame Revolvers

J-Frame Revolvers

image of j-frame revolver
closeup of j-frame revolver

The Smith & Wesson (S&W) J-frame is the smallest class of its revolvers. S&W had two frame sizes in 1894 when it designed the side swing or swing-out-cylinders line of revolvers. The smaller-sized frame was called the “I-frame,” and the larger-sized frame was known as the “K-frame.” These designations were an internal way for employees to identify the frame sizes. However, S&W employees began using the internal frame designations in discussions with journalists, leading to their widespread use.

The J-frame was introduced in 1950. Ten years later, the smaller I-frame revolvers chambered for the less-powerful .38 S&W cartridge were discontinued. All small-frame guns made since have been built on the J-frame. 

Did You Know?

A 200-Year-Old Legacy of Entrepreneurship

The Wesson family can trace their history of entrepreneurship back 200 years. Massachusetts native Rufus Wesson (1786-1873) was an expert producer of wooden plows. His sons Edwin (1811-1849) and Daniel (1825-1906) became gunsmiths. In 1852, Daniel Wesson partnered with Horace Smith to establish the Smith & Wesson Company. The younger Wesson brother Franklin (1828-1899) also pursued a career as a firearms manufacturer, partnering with his nephew to found Wesson & Harrington (later the Harrington & Richardson Company).

Historical photo of Smith and WessonFactory in Springfield, Massachusetts
Smith & Wesson Factory, Springfield, Massachusetts, circa. 1908 (Image courtesy of the Library of Congress)

K-Frame Revolvers

k- frame revolver
image of k-frame revolver

The S&W K-frame is larger than the J-frame. It is one of S&W’s original models that has a swing-out cylinder. Like the I-frame, it had been around since the 1890s. It is known as the “.38 frame,” as it was designed specifically for that cartridge.

L-Frame Revolvers

L-Frame Revolver
image of l-frame revolver

The L-frame was designed to be a sturdier K-frame. This was accomplished by adding more steel and greater strength in critical areas to handle the power of the .357 Magnum. It became one of the most popular duty guns of the time.

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