"The durability of� the mechanism� of the Chauchat� automatic� rifle has� been� questioned.� Experience� has� proved� that� this objection� is not� well founded,� if care� is taken not to remove the rifle from its case until the moment� for its use.� Mud is one of its principal enemies. "
from note pg 13 here pdf Supplement to instructions (provisional) issued January 8, 1916, on the offensive of small units.