I removed a pistol grip from an AR I own and am replacing the grip with an Ergo grip. For the life of me, I can not get the pistol grip screw back in and frankly, I'm afraid I'm stripping out the threading in the receiver, if not in fact basically tapping a whole new threading! I stopped trying to get it in...but what do you recommend? I'm using the same screw that I had to remove to install the new pistol grip.

Suggestions?