I have a pre-ban H-bar 14.5" carry handle.  I will be getting the tax stamp from the BATF prior to the commencement of any part of this project.  I was just wondering if my standard barrel and bolt carrier will need to be upgraded or replaced, or if they are sufficient?  If it's not a necessity and just a good idea?   I've heard the barrel needs to be chrome lined, but not sure if that is a rumor or necessity.  Anything else I may need to know.  Thanks.

Tax stamp for what?  A LL or DIAS?