H & R continued to offer the 24-gauge in both their small frame and regular frame singles through the last H & R catalog I have, 1935.

J. Stevens Arms & Tool Co. offered some of their single barrel guns in 24-gauge --

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By the 1919 J. Stevens Arms Co. catalog the 24-gauge is gone from the No. 105/107 offerings.

Remington Arms Co. offered their side-cocker singles in 24-gauge --

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but got out of the break-action gun business in 1910.

I don't have a lot of Iver Johnson paper but they did offer their Champion single in 24-gauge in their 1919 catalog --

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the 24-gauge is not offered in the 1931 catalog.