When was the Hatcher Hole introduced?

Was the Marine Corp the first to implement it?

Marine Corps implemented it first

I have a few references that say 1936. Canfield says the Army mandated it in July, 1935. The U.S.M.C. followed a short time later.

Also around this time the bolts' gas escape hole was enlarged.

Would it be possible for the gas escape hole on the bolt to be enlarged but not have a hatcher hole put in?

Jarrod