As others have said, headspace is set by the extension and has absolutely nothing to do with the carrier or bolt.
If anyone is unconvinced then mate a new complete bolt carrier group to a new barrel. This is
100% unnecessary but might make you feel better.
ETA: I completely understand why someone would ask the questions, and respect them for doing their research. There are MILLIONS of AR rifles in US civilian hands. In fact, I read over the weekend the ATF believes there are 5-11M AR pistols currently. That is just pistols! Companies like PSA have taken "home building" to an entirely different level. It has introduced a lot of people to ARs that woud have otherwise not been interested. I would guess a lot of these folks know very little to nothing about gunsmithing. This combined with the omni-present amount of USED AR parts floating around the internet would likely result in countless lawsuits and posts about problems resulting from mixing new/used and home brewing junk if there was an issue resulting from using old/new components. However, it is rare to see any of this. For reference, I built my first AR15 from a worn out USGI parts kit on a SGW stop sign lower sitting at my grandmother's kitchen table in 1984. Parts kits back then came in a sealed blue plastic bag filled with a mix of M16 and M16A1 parts combined with dubious quality semi-auto fire control components. Barrels could be H&R, SAK, GM Hydra or Colt, etc. Bolts were usually Colt for some reason. Carriers were unmarked and I suspect they were some 3rd party replacements. Guns built from these kits just ran and ran and ran. Back then you really only had a couple of options if you wanted an AR15. You bought a factory Colt (which I did later that year) or you built one from these kits on an (Olympic) SGW lower (or cast EA ... not Eagle Arms ... lower a few years later). Heck, I had one of these ran over by a tractor and it didn't even loose zero. Anyway, back then there was a "staple" vendor at every gun show. Actually usually two or three. These guys would have bins FILLED TO THE TOP with surplussed M16 parts for your home build. This went on for years so I'm assuming people weren't KB'g their home built guns compromised of "who knows how much use it had before it was DRMO'd" parts thrown together in someone's garage. I won't even get started on the craziness that happened when Colt introduced the "HBAR" and everyone had to upgrade their "now worthless pencil barrel" A1 to an A2 or even worse HBAR. Suffice to say, people were cranking off their barrels and replacing them while not even considering changing the BCG or bolt.
Sorry for the wall of text. I am old and rambling.