Thanks Jim; Serial Number 182927 identifies the last Mono SBT with the 4 bird version on the left side. This completes a 21 year span of Mono SBTs with the first (a 2 Bird version) produced in 1920 (S/N 13578) and yours, the last in 1940. As previously noted S/N 127781 is a documented 4 bird version and is the earliest know 4 bird SBT version, produced in 1930.

An article on this subject appears in the current issue of the LCSCA Journal and pleads for pictures of doubles with serial numbers higher than 220639 showing 2 dog engravings and lower than 104695 exhibiting the 4 bird version. As of this date none have been offered so it appears the records for these guns shall remain unchanged