The Smith buttplate is commonly found on c. 1890-1910 0 to No. 2 grade guns. No "Trap
Gun" was advertised in the pre-1913 catalogs, and the buttplate was likely a marketing tool to promote Smith guns for the increasingly popular sport of trap shooting, and tied into the new Pigeon Gun which was introduced in 1894 (though the first run was completed in May 1893.) See
http://docs.google.com/View?id=dfg2hmx7_343dn6phncv
The Trap
GRADE gun was introduced in 1913
LOTS about Folsom, and the Parker Trap Gun they marketed with a
different buttplate, here
http://docs.google.com/document/pub?...hfguSXXQ&pli=1
And
another after-market plate that is not uncommon