Thread: Tikka barrels questions

Looking at Stagstalkers post about shortening Tikka barrels made me think about this question .How is we are told you cant ream out Tikka barrels as its to hard and wrecks gear .Yet we see they can cut threads no troubles, i'm no engineer but i would have thought the barrel would be just as hard on tools working on the outside ,its the same piece of steel isnt it ?? . I know the processes are different but i just would like to know why .