I just installed a set of Truglo TFO's on my 36.After tightening the hex nut as tight as she would go,the front sight is very loose,i can wiggle it with my finger. Seems as though the nut is to short. I tried using the stock nut that came with the gun but it was way to long. Can i purchase a different nut size? Should I contact the seller and make him aware of the prob?