When were Marine Corp sights first used?

[Mike D]

From Canfield's "An Illustrated Guide to the '03 Springfield Service Rifle"

Marines during WWI thought the m1917 sights superior the the 03's in many ways.

They ordered 10,000 sets (front blade and rear ap) from SA in Oct. 1918, first manufactured in 1919.

Sheet metal cover was produced for use with such sights.

Remained in service through at least 1936, and some have been found on original 1903A1/Unertl sniper rifles used during WWII.

Not doubting the other info, just what I read.