I was cleaning my new AR-15 and one of the gas rings was very worn out and the small gap in it was now a huge gap, the ring just fell right off. Two questions. One, Will if function with only two rings? Second, do places like gander mountain or something like that sell gas rings? Or do i have to get a whole new bolt with them already installed. Im in Dayton ohio and would like to go pick up the pice instead of waiting a week from ordering it on the internet. Thanks.