I have been looking around at some of the “interchangeable” rounds, according to the gun ads anyway, like the 7.62/.308 right through the .357 magnum/.38. I know that bullets that are very close are not always interchangeable especially in semi autos but can they be used in manual guns - bolt, pump, etc? If so what calibers can be used this way without messing up the gun or the shooter? I can never find any hard facts on the subject only internet forums some better than others. Is there anything out there that someone can point me to that has more proof than someone’s good word?