Manufacturing Codes on M1918 Colt BMR/BAR Sights and Butt-Plates

[TGCJ]

Would any M1918 Colt Browning Machine Rifle/Browning Automatic Rifle owners like to share the manufacturing codes on the butt-plates and rear sights of their guns? My sample of two Colts have one "R" and one "E" marked rear sight leaf and a Winchester "W"  stamped on the inside of one butt plate trap door I examined. Since these parts were unmodified M1917 rifle components it makes sense for Colt to have acquired them from the three makers of M1917 rifles. From my two-gun sample it appears parts from all three makers may have been used by Colt. I am curious to know what the manufacturing codes are on the rear sights and butt trap doors of other Colt M1918 guns. Marlin too.

I have been looking thru "Rock in a Hard Place" but have not found it especially useful for details on M1918 guns - lots of filler. On page 35 it states that the M1917 rifle rear sight leaf was 2 5/16 inches long while the 'modified' sight on the BAR was 2 1/16 inches long. The "M1917" sight leaf in the illustration is from a British P14 rifle which had a longer sight leaf. I am not in the same location as my BAR but I am fairly certain that the M1918 rear sight leaf was identical in length to the one on the U.S. M1917 rifle.