Originally Posted by MikeSantor
Ie earlier gen 3s did not have them and later ones did, etc?
^^^ This, if it followed the same progression as the G30 frame (same frame as G29).
Judging from the Glock Serial Number Research Project
, it appears the G30 45ACP starting showing up with an accessory rail around June, 2005 with a serial number prefix of HGM.
The first entry in the database for a G29 specifically mentioning a rail is serial number HXN*** with a Born On Date of 2006-02-01 (Yr-Mn-Dy)