For what it's worth, I was looking around on Grant Cunningham's blog last night (thanks to MrBorland above), and was somewhat gratified to find that he has a write-up about working on one of these guns:
http://www.grantcunningham.com/gp-100_100906.html
He even uses a picture of it for his "ad" on Rugers:
http://www.grantcunningham.com/ruger-gunsmithing.html