According to Farris the EN on a striker or C'cking piece is Eddystone. The other original parts were made at the 3 manufacturing plants and marked E, R or W.

I have a WW II bolt body marked with a flaming bomb and a K. I don't know who made it.

Johnson Automatic made replacement barrels.

As far as I know there is no list of sub contractors for replacement parts.

Doug