ISO: Case Neck turning of a modified 6mm case

Looking for someone in the Bismarck/Mandan area that might be able to help me out. I have a custom modified case that needs to have the neck OD trimmed back a bit to fit my chamber. I worked with Hornady to have a custom modified case made for my 6 BR and they can't seem to get it right. Hoping to find someone that could trim the OD of my case neck and see if that solves the problem.

Thanks in advance if anyone can help me out, much appreciated.