The M1 Garand did not spring into troops’ hands as a fully thought-out battle rifle. Garand thought he had the design of his new semi-auto military rifle perfected when he was told to go back to the drawing boards and change it significantly.In fact, it took years of hard work on the part of John C. For instance, his rifle was initially built for the then-serving American .30-caliber cartridge.
Also worthy of mention is Winchester barrels are not dated but do have a “WP” stamped on them (for “Winchester Proof”).
Springfield Armory barrels are stamped with the month and year of production.
Towards the end of WWII an improved rear sight designated T105E1 was developed but according to Bruce N.
Canfield’s book Complete Guide To The M1 Garand And M1 Carbine, it is unlikely if any Garands issued during WWII wore them.
So rebuilt M1s can be found with Springfield Armory receivers and Winchester barrels and vice-versa.