Yes that is correct. The cartridge still headspaces on the shoulder ( i.e. shoulder to boltface). All i meant was that Mauser action barrels are tightened/torqued against the C to assure the correct headspace. This way you can have multiple barrels fit the same action without having to rely on tightening nuts, etc. same can be done with winchester, tikka, etc. but there the barrels are shouldered and tighten against the front receiver ring. On Remington and some clones you have the recoil lug between them and then the thickness of that ring is important if you change that. Some aftermarket Rem clones have an integral recoil lug machined as part of the receiver ala Mauser or Win. The beauty of the Mauser is that the barrel chambering, threading, etc. is a bit simpler as it is just flat without a cone or relief cut for the claw extractor. So you always have to torque Win-like barrels to the same torque. On Mauser (or rem with cone breech but no claw extractor) you can just tighten the barrel and depending on torque, the headspace will most likely change only a thou or two at most from hand tight to “sob that’s really tight”. So running a prefit barrel on those is easier. When changing barrels one should check for proper headspace regardless of the method but improperly toqued CRF win-like barrel will not let you close the bolt. Which for some, may be a good thing.
Sorry for the verbal diarrhea.