I know this isn't C&R, but I am looking for help regarding a Preban Polytech M14 I have the opportunity to buy. The rifle is in very good to excellent shape, and the cost is $699. I know I have heard in the past that either the norinco or polytech (or both) have defective bolts that can cause excessive headspace, but what is the truth?? Also, how reliable & accurate are these rifles?? Is this deal worth it, or should I save my money for something better??