Since nothing on upper is changed, except the barrel of course, I would believe that doesn’t affect the zero.
I have several weapon platforms that are capable of barrel changes such as MRPs, SCAR, XCR, DTA SRS. Each of those have some degree of zero change with removing and replacing the barrel. Usually, it is under 1 MOA, but this is significant on a precision weapon. Thus, I confirm my zero on any weapon that has the barrel removed.