with any cartridge, the neck should expand on firing such that a bullet will be a loose fit in the neck. the neck will have to be resized, and expanded to give the next bullet correct neck tension. the case body might still easily enter the chamber, and if so will not need sizing. however, in a dangerous game rifle, sizing the case as well is wise to guarantee every cartridge will chamber absolutely reliably. always measure case length however you size, as growth can reach the chamber transition causing pressures to skyrocket. best case life involves both partial annealing and minimal working of brass using dies that are not undersized for the chamber. polishing out a sizing die can be done with some research. not overloading also prolongs case life. the belt is designed as a headspacing method. otherwise a straight case would need a rim, or to headspace on the case mouth like a 45 acp. in the day, belted case could be made well undersize to easily chamber in bolt actions better than rimmed cases. the belt gave good headspace on loose cases, and fed from magazines better than rimmed. guys tended to leave brass on the ground then, so over working of brass was not an issue. also manufacturing tolerances were less tight than now, so looser fit was better. now we use the shoulder to headspace belted bottleneck rounds that we reload, just like any rimless round. straight cases still headspace on the belt when reloaded. when neck sizing only even with lighter pressure, sooner or later full length sizing will be required. with straight cases ( which still have a little taper), the fl die can be backed off to size less in many circumstances. with bottlenecks, the shoulder position must be maintained. the new breed of magnums have no belts. the marketing machine says that this produces improved accuracy over belted. the rub here is that if you believe that you must accept that the same companies are indicting their own loading practices when they load belted ammo. bruce.