I have never own one before much less ever try to build one wonder if I have messed something up on building the lower im guessing same way you would build a Ar15. Everything is brand new trigger works bolt catch is not catching I have come to figure out the charging handle I have fit correctly and have been told the rubbing I am hearing is from it being brand new. The problem is the bolt catch it not catching to keep the bolt back. So I need to know what stupid thing I could have possibly done or adjust to make this work correctly.