I can't find Loomis in any of my references. If it is a utility grade, double barrel, probably with side hammers, I will guess that you will discover Belgian proof marks under the barrels. Look for an oval surrounding the letters ELG or a mark that looks like the Washington Monument. Several million similar guns were imported to the US c. 1880-1915, marked with several hundred trade names. If you know the location where it was acquired c. 1900, check the old business records for a Loomis Hardware or Loomis Mercantile store.
Joe Vorisek wrote the book on old shotgun markings, and his listing says: WM LOOMIS - name found on Belgian hammer shotgun with damascus barrels, maker unknown. I'm assuming this is a breech loading gun, so it would have been made sometime after 1865 and before 1915. You might search for any reference to a William Loomis who owned a hardware store or general merchandise store in that time period. Many stores paid a couple dollars extra to get a dozen or so guns marked with their own name.
There is a wealth of information by Nick Niles in the Gun Digest book of Guns and Prices 2005 Edition, ISBN #0-89689-324-3 and library of congress # 2005906853 Models, prices, and history. Also acomplete listofALL the names associated with Crescent F.A. Co
Not more than 100 USD or so
Gertrude Schoepperle Loomis has written: 'Tristan and Isolt' -- subject(s): Tristan (Legendary character), History and criticism, Romances, Tristan and Iseult 'Medieval studies in memory of Gertrude Schoepperle Loomis' -- subject(s): History and criticism, Medieval Literature, Comparative Literature
The address of the Loomis Library is: 6050 Library Dr., Loomis, 95650 0610
Jan Loomis has written: 'Pacific Palisades' -- subject(s): Social life and customs, Pictorial works, Biography, History
The address of the Loomis Public Library is: 301 Commercial, Loomis, 68958 0226
John A. Loomis has written: 'Texas ranchman' -- subject(s): Biography, History, Ranch life, Ranchers, Social life and customs
Chauncey C. Loomis has written: 'Weird and tragic shores' -- subject(s): Biography, Discovery and exploration, Explorers, History, Travel
The phone number of the Loomis Library is: 916-652-7061.
The address of the Loomis Basin Historical Society is: Po Box 2195, Loomis, CA 95650-2195
Lorell Loomis has written: 'Loomis legacies and a saga of Sanders'
The phone number of the Loomis Public Library is: 308-876-2334.
Loomis Homestead was created in 1640.
Loomis Chaffee was created in 1874.
Samuel Loomis was created in 1978.
Carol Loomis was born in 1929.
Robert Loomis was born in 1926.
Chauncey Loomis died in 1817.
Gustavus Loomis was born in 1789.
Gustavus Loomis died in 1872.
Sabra Loomis was born in 1938.
Robbie Loomis was born in 1964.
Henry Loomis was born in 1919.