Hopefully the rack is mounted directly into the studs or concrete. I've seen them crush gypsum between the stud and paint too...
I'm not much help, but they all suck. I've bought probably 2k worth of universal sliding rails to attempt with various servers. I don't know why but none of them fit properly. None of them slide properly. They are all just annoying. I gave up with them. I bought the OE sliding rail kits for my various servers and magically everything works perfectly.
For servers where I want to move them in and out but don't want sliding rails, I just buy those universal L bracket type mounts. The servers slide well enough on them, they're just powder coated bent steel. And a single screw from the front panel into the rack keeps it secure enough since the weight is being held by the support, not its own ears.
That’s solid info, thanks! Looks like the OEM rails aren’t “technically” designed for this model. Or the one they have won’t fit my space. I have like maybe 22” until I hit the wall, and most of the rail kits SilverStone has seem to be minimally 22” which wouldn’t account for any rear vent and or power cord space, if it would even fit on my 20” rack.
FWIW I do have the rack lag bolted in 4 spots to a concrete basement foundation.