Just reviewed the surplusrifle.com article. For a rimless cartridge to extract and eject properly, a counterbored bolthead appears to be necessary. The author discusses adding a ring to the boltface using silver solder, and comments on the effect on temper; he suggests that brazing is too hot. Any true silver solder that I have used required red heat. Red heat is going to change any tempering that was done to the bolthead. Whether this would be a problem or not, I do not know. There are silver bearing solders which flow at a cooler temperature, but are not as strong. In addition, if a ring is added to the boltface, it may well position the case for extraction and ejection, but what would happen in the event of a casehead failure? I am sure that pieces of the ring would depart the rifle at high velocity. In the single shot experiment which I did, I counterbored the original boltface, and brought the barrel breech back to the bolthead. If I were to add a piece to the bolthead, I think that I would cut the head back, and add a cup shaped piece with a counterbored boltface. Any load on this joint would be in compression, not radial. The new piece could even have a cylindrical tang which would extend back into the bored out firing pin hole. This would increase the area for a silver bearing solder joint. A new, smaller diameter firing pin tip could be fitted to the new boltface. The barrel breech could be in its original place, the boltface being extended toward it. In a .303 rifle, there is a gap between the boltface and barrel face equivalent to the headspace. This gap is unnecessary and undesirable when a rimless round is used.
