I assembled an AR this morning, I used a "AR Fifteen " brand receiver. The pivot pin detent hole is not round. I did not notice this until I had inserted the spring and the detent. It is stuck. I  made the mistake of pushing it in a little hoping it would dislodge it . Now it is really stuck. Tried lube and an air hose with no luck. Beat the receiver with a rubber hammer and swore quite a bit with no luck. Anyone have any suggestions?