thanks for your reply.
I replaced the bolt catch with all colt parts. it helped but did not fix the problem. I do believe the lower is probably out of spec a bit. I have a second rifle that has the same identical lower unit that I gave to my brother. I was able to look at it over the holiday we i was back and it seemed to be working fine all the way around. BUT its like new. I don't think it has had much use, where as i carry mine on duty everyday, and have range qual/training 4-5 times a year, so it has been used. I think I will have the lower fixed or just get new one. I can not afford to have any doubts as to how it will perform.