Got the barrel and wrapped real nice,had the rubber caps on each end and no damage to the box. Problem is there is burr/ding on the extention and, there seems to be a slight raised ridge on the end of the extention as well. like it was not machined completely. This is going on my Maten upper/lower set I got from you a while back. I have a DPMS SASS barrel that slides into this upper with no problem so I know there is'nt a problem with the upper. I gently tried it to see if it would start to go in with the ding indexed to the slot in the upper but no joy. Did not want to try sand or file anything until I hear from you or, if you want me to send it back?