The Sterlingworth was introduced in 1910 and marketed under the bogus name The Sterlingworth Co. From the 1910 The Sterlingworth Company catalog --

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The first couple hundred guns have an address of Wayne Junc. on the roll-stamp on the left barrel.

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After that they went with a Philadelphia address --

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The Sterlingworth appears as a product of the A.H. Fox Gun Co. in the 1911 A.H. Fox Gun Co. catalog.