I just want to verify my G21 frame is normal. When I remove the slide the rear slide rails are perfectly even and flush vertically with the polymer frame. The front rails, however, are higher than the polymer frame. About half the thickness of the front rails are above the polymer. Basically, it looks like they may have not been embedded deep enough. I checked my 9mm and .40 Glocks and both the front and rear slide rails all rest generally even with the polymer. Is a higher pair of front rails normal on the G21? I know the slide is supposed to be loose just like my other models but when assembled I have a ton of vertical play in the front of the slide. The rear is as tight as my other models though. The height difference is clear just by looking at it. It is not such a minor case that you need to run your fingers across it to feel it. I am worried that the machine that holds the rails as the frame was formed around them may have been out of spec the day mine was made. I'll post pictures when I get home.