Foxy,
I've spoken with other 1911 owners here (still a "semi") and read a good bit on this same subject. There is almost 100% agreement that semis do have to be lubed. Bill Wilson even has a You Tube video on it that features his own "special sauce", which I have:
[ame]https://www.youtube.com/watch?v=t4D2mRlDo48[/ame]
As much as I paid for that darned thing, I don't want problems at the range with my Wilson Combat 1911 or to have to send it back to "The Mother Ship". Other forum members have also their own lube preferences - Frog Lube, Mobile 1, Rem Oil etc.
IIRC, it was the alloy in the slide, which was different from the frame, that caused my problems. There was no possible movement at all for me. Afterwards I switched from "Shooter's Choice" (red) to lithium grease (white) which was the same that we used at the ranges in the Marine Corps. It's also a lot cheaper than Bill's "special sauce".
This may not be the situation (problem) for your S&W 4006. It's just a possibility.