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.
The Constitution is not an instrument for the Government to restrain the people. It is an instrument for the people to restrain the Government!
“Americans have the right and advantage of being armed. Unlike the people of other countries, whose leaders are afraid to trust them with arms.”
James Madison. Author of the 2nd Amendment