Since the scope/sights are not loose on the upper, the accuracy of the gun can only be lost because of the extra movement in the gun. It would be basically like not holding on to your gun very tight when you shoot it. I have seen the wedges and different means to tighten things up and they do seem to work. But to your question, in my experience the normal amount of play you find in 99% of the AR's out there have not effected my shooting them.