@dar, we have several experts on tokens here (this list sadly does not include me). Until one of them weighs in, I can tell you what I'm seeing in my '97 edition of Rulau's Standard Catalog.
Catch Club has two different sizes of tokens, 27 mm and 26 mm, all of which are excessively rare (R6s, R7s, or R8s). There is mention of a silvered copper version of HT# 403A in the Boller collection that was "silvered copper and 30.5 mm". Any chance that is a good match for your example? Also, I note that the #405 is silvered brass. Maybe consider doing a specific density test on this piece to determine what alloy you have? I can't tell what yours is, but Rulau states that these were made in copper, silvered copper, gilt copper, brass, and silvered brass.
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