Hole's in the screw (and in rear of carbine tubes) to drain water. Screw length is what can affect function.
I've used the screw you get with a Magpul grip as a replacement on a Gen 2 PRS. Don't know if they're the same screw now.
Away for a funeral, will check when I get back. Shoot me a PM in the next day or so if you have not got one. If it came with the PRS, I should have one and it will be all yours.