I belive its induction heated on.. meaning they heat up the front of the action, the metal expands and the barrel is pushed into the reciver. Sealing it when it cools again.
They do the same thing to the "tail of aircrafts" so its pretty sturdy solution.
The only thing I have against the M12, Sauer 100/101, is the irritating mounting solution. I hate mounting bases with screws.
That is why I vastly prefer integreated bases on the action, ala Sako/Tikka/CZ.
I was myself considering the M03, but I belive I will rather go with 3 Tikka T3x. 222/308/9,3x62 with McMillan stocks.