** That is correct - found a web site with 1963-1964 photos of gunners with M-60s being held by hand on their laps in open cabins with no mounting posts or other support brackets. **

Thank you, my friend; just so there's no misunderstanding, you might be interested to know that the photos you refer to are of a Huey B-model gunship. B- and C-models never did get hard mounts for the door guns. Carl and I were discussing the D-model slicks, a different airframe, most of which had hard mounts later on.

Bob Kilpatrick