It is a grade 1 Flues- made from about 1906 to 1924-- I don't have a sn chart at hand- but if the extractor forearm (snap-off- no latch) does not have an extra machine screw to anchor the forearm iron, it usually means pre-1915 era. Check for short chambers, and receiver cracking- Flues were black powder era guns-- The later NID's are A-OK-- RWTF

"The field is the touchstone of the man"..