Case & Sons, there have been many different stamps used on its knives.
Shields, bone & other handle cover colors & styles, jigging patterns, hafting techniques & more can be used for further validation.
Shopping trusted sites & trusted knife dealers is something we highly recommend to all beginner & intermediate collectors.
Thankfully, we have trusted sellers in the AAPK member stores where you can buy with confidence. You will find that most books date this stamp as being used from 1920 to 1940.
I have found that many serious knife collectors disagree with this date range and say that it was actually used from 1919 to 1945.
You can learn to date Case knives by marks once you know where to look. This is the master blade; it is usually where marks are made. The tang is at the end of the blade where the pin anchors it to the casing.
You may need to clean this area to see marks but if the knife is a Case, that's where you'll find the mark. Case filled an order for 81,000 knives for the United States Navy just before World War I and provided a custom survival knife for the astronauts on Gemini and Apollo space missions. This same C appears with an extended line under the ASE of Case and X or TESTED XX below the line. Case & Sons of Bradford, Pennsylvania began making Case knives about 1905. The company continued through 1940, but used other marks at the same time, including the short-tailed C with an arrow point at the top. In the 1980s, the same dating system was used -- with two subtle differences.First, a "Lightening S" appeared in both "CASE" and "USA." Secondly, the dots were placed above the "USA" From 1990 to mid-1993, the dot system was replaced with a stamping of the actual date.Year Symbol Chart ( Types of Buck Knives (com) Camillus Tang Stamps and Dates ( Camillus Tang Stamps circa 1915-1946 -A WORK IN PROGRESS (AAPK-All About Pocket Knives) The Tang Stamps of Adolph Kastor, Camillus and Their Cutlery Relatives (Knifeworld) Street Cutlery (AAPK-All About Pocket Knives) Carl Schlieper German Eye Works (straightrazorplace.com) Case College Tang Stamps ( Case Tang Stamps ( Identifying the Age of a Case Knife (AAPK-All About Pocket Knives) The Case XX – Secret Code (Shepherd Hills Collectors Club) Case XX Folding Knife Tang Stamp Dating Video (You Tube) The History of W. Case & Sons and Related Companies (iknifecollector.com) Case Factory Knives ( Case Factory Pattern Number Reference Guide (AAPK-All About Pocket Knives) Case Knives (AAPK-All About Pocket Knives) Old Case XX “Family” Tang Stamps (Trent Rock’s flickr page) Cattaraugus Knife Numbering System (AAPK-All About Pocket Knives) Cattaraugus Knives (AAPK-All About Pocket Knives) Great Eastern Cutlery (AAPK-All About Pocket Knives) Imperial Tang Stamp Chart ( Old Imperial Tang Stamps (AAPK-All About Pocket Knives) Kershaw Markings on 1050 ( Puma Knives ( Puma Knives Dating (Puma Knife Man) Queen Cutlery Tang Stamps ( Queen City Tang Stamp (Terry Truett’s Photobucket) Google Book Review of American Premium Guide to Knives and Razors: Identification and Value Guide (Google Books) The History of Queen (AAPK-All About Pocket Knives) Remington Tang Stamps (AAPK-All About Pocket Knives) Remington Knives (AAPK-All About Pocket Knives) Remington Scout Knives (ibdennis.com) Remington Knives (AAPK-All About Pocket Knives) History of the Robeson Cutlery Co.