When you install them on the backstrap, are they supposed to go down into the grooves in the backstrap or are they supposed to lay on top of the ridges?
Very good question! One I struggled with and put too much thought into for too long before installing them.
I finally realized that it they were not meant to go into the grooves: 1)The holes in the rubber wouldn't be round; 2)It would have been precision cut to fit into the grooves; and 3)More grip is needed on the back and front than the sides, therefore it made more sense for the rubber to lay on the ridges.
I honestly still can't figure out why they made the backs with round holes, or even why the cut-out isn't continuous around the entire back...?
I also had problems laying it on and having the curvature right (ie not creasing) so I cut it and only put on the bottom part:
Same question for the front checkering. I haven't installed them yet, but just from laying it on the grip and seeing how it fit, seems like it fits nicely around the ridges on the side of the grip, but when it goes around to the front it seems to lay on top of everything. I figured the grips would go down into the grooves on the front like it does on the side.
Exactly correct. During installation, after I thought about it for a while it made sense for the rubber to go on the ridges in front - for grip's sake. My guess would be that it goes between the ridges on the sides for purely cosmetic purposes:
Remember that extra rubber I had from cutting the back portion up? Look again at that last pic... I took a piece, trimmed some more and added it above the grip safety. It makes sense in my head to put some there but to each their own. Not sure if it actually helps but it feels good.
Also, being right handed I did not add the thumb piece on the right side. My trigger finger was getting a little grip from it so I took it off and it's more comfortable to me without it.