I would bet a months salary that it has been rebarreled. I have one of these that I converted back to original with a NOS K43 barrel. I have one that someone rebarreled into a .270 and I rebarreled that one back to an 8mm with a used K43 barrel.Must be a new barrel (unless the barrel was bored out for a 30 caliber sleeve. Even then, I need to look at the reloading books to see the diameter of the case to see whether the chamber may be bored out. If no to both, then it's a new barrel (there were probably plenty of surplus barrels that could be fitted to another gun).