Seems that these air pistols have been getting a lot of attention from enthusiasts recently.
It was the very well illustrated and written post here on the BBS by John G., documenting his own progress that finally got me motivated to build one for myself.

http://www.network54.com/Forum/40594...ing+Air+Pistol

John's original post, alluded to above:
http://www.airgunbbs.com/showthread....hiting-Project