Yesterday at the big gun show I saw a Gen 3 G21SF with a full pic rail on the dust cover. Not the Glock style with the one groove but the full rail just like a Timberwolf frame. I picked up the gun and it was a Glock frame and appeared to have a Glock SN but for some reason I didnt commit it to memory to check it later. I have never seen a Glock frame with a full rail. I know a whole lot more about Glocks than most and Im the friend everyone goes to for Glock questions but I have never seen this. Ill include a pic of my Timberwolf that has the same style rail for reference. Anybody know anything about it?