Hey everybody. I am working on building an AR-10. I have an Armalite lower and purchased the two-stage trigger kit for it, which came with a standard A2 pistol grip. My problem is that I have installed the grip and gotten the screw tight, but when I grip the pistol grip I can rock it back and forth. I don't know why this is happening or how to fix it. The screw is as tight as it is going to go. I didn't forget to install the washer. Has anybody experienced this before or have any advice as to what the problem could be? Thanks!