In our shop we call this procedure the Robin Hurt conversion. As it was Robin, at an SCI Convention, who made us first aware of the necessity to do so. It seems he had the bolt handle come loose on one of his personal G-series Model 70s. We took note of what Robin said and filed it away as a "act of God" failure. Not 60 days after the SCI convention we had the very same things happen in our shop. Now we took real serious notice. Having the bolt handle fall off a rifle is not a situation we wanted one of our clients to face.
Our solution was to set up every G-series Model 70 bolt in the milling machine, drill and ream a 3/32" hole through both the investment cast bolt handle collar and the bolt body and then solder a 3/32" dowel pin into the new hole. The pin is then filed and polished flush with the major bolt diameter and the same is done in the inside diameter of the bolt body. The bolt handle and the bolt body are now joined mechanically in addition to the original copper induction brazed joint. No fuss, no issues later on.