The trim rings found on earlier examples have been abandoned, and the top section on these is fixed, so there's no more unscrewing them and losing the clip. Unfortunately, the top example in this picture is missing the knurled plastic piece, which is a shame (on ebay, it had a large rubber eraser over the top which hid this problem).
Barrel imprints appear either at the top opposite the clip, or as two in this picture show, just above the lower barrel section. Notice also the one second from bottom has a longer lower barrel and shorter upper barrel . . .
NOTE: This article is now included in the print version of The Leadhead's Pencil Blog, available anywhere you buy books, or also from The Legendary Lead Company.
To order, here's the link: Volume 1 at Legendary Lead Company