I bought a 2 piece 6.5 inch quad rail from Combat Optical for 49.00 and it came with a delta wrench. There is a guy on you tube who slapped his right on, not me. The bottom half was no problem but the top half I cant get on right. The gun is a Rock River operator Lar15. I really don't want to take the gun apart to make it fit so I was thinking it would be okay to grind the lip down (that seems to be the hangup) flush with the delta ring. It should stay secure from the top of rifle and the 4 allen screws attached. The other thing would be to send back. Does anyone have similar problems installing or a suggestion? Thanks very much.