Wikipedia
Driggs-Schroeder was the name of several naval guns designed by US Navy officers William H. Driggs and Seaton Schroeder for the United States Navy in the late 1880s, fitted on ships built in the 1890s. Driggs later founded the Driggs-Seabury Ordnance Company ca. 1898 in partnership with Samuel Seabury, a retired US Navy officer.
Driggs-Schroeder weapons included 1-pounder, 3-pounder (Navy Marks 2 and 3), and 6-pounder (Navy Marks 6 and 8) naval guns. All were rapid-firing, what today would be called "single shot", with brass cased ammunition. They were among numerous models of these guns equipped on US Navy ships of the 1890s. Other manufacturers' designs included fully automatic 1-pounder and 3-pounder guns, but not Driggs-Schroeder. Most Driggs-Schroeder weapons were manufactured by the American Ordnance Company, with some manufactured by Driggs Ordnance Company.
Some of the ships equipped with Driggs-Schroeder guns included USS Texas (1892), USS Maine (ACR-1), , , and . Olympia is preserved with her Driggs-Schroeder 6-pounders intact at the Independence Seaport Museum in Philadelphia, Pennsylvania.
Sources indicate that Driggs-Schroeder designed a 3.2-inch field gun for the US Army, possibly the M1897 and perhaps the same gun later manufactured by Driggs-Seabury. An Army 4-inch/40 caliber Driggs-Schroeder rapid-fire gun also existed, probably the same as one of several Navy guns of this type. Only four were emplaced by the Army in coast defense mountings; two at Fort Washington, Maryland 1899-1921 and two at Fort Warren, Massachusetts 1899-1925. Driggs-Schroeder designed 6-pounders designated Marks II and III for the Army; they possibly corresponded to the Navy Marks 6 and 8. Some of these were deployed in experimental quantities in coast defenses on "parapet mounts", wheeled carriages with fittings that allowed them to be secured to pintle mounts. A dozen were deployed at Fort Ruger in Hawaii as part of the Land Defense Project of 1915.