Inland production shows a 6,300,xxx serial to be mfg from Aug 44 - Nov 44 (6219689 - 6449687)
Flat bottom stock, not an M2 fat bottom stock. Probably re-arsenaled post war for the bayo lug (more than likely)
As to late production, sorta but more middle late than late late. Inland made 3 more batches with the last being Aug 45... but certainly yours was made within the last year of production.
Shoot it yet?