You just can not exchange bolts unless the spare has the same head space as the original. Even though a lot of people buy a bolt for an AR upper, even at that it is not always a sure thing. The moral of the story anytime a bolt is purchased separately for an upper or in the case of switching bolts in a bolt action or any semi-auto rifle. The weapon should be checked for head space before firing. The failure to check for proper head space can result in what in the industry calls a catastrophic event! "BLOW UP"! Even in the AR Rifles/M-4/M-16 rifles there is mil-spec tolerance differences. For example in the Chamber and the Bolt dimensions. The single part by it self would fall within the mil-spec tolerance but put the two parts together there could be a serious problem. If one is on the high range of being over tolerance and for example the bolt would be on the side of being under tolerance. You would have a problem. Problem with buying spare bolts for the bolt actions they are fit to the gun as far as head space. And you would have to have a professional attempt to match the two bolts with the barrel set.
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