I owned a Steyr SSG Police that the barrel jumped forward out of the receiver on while firing it.Rather creates a headspace situation! I was intending to internally rethread the receiver and reinstall a new barrel but Steyr came good for replacing the rifle with a new one so didn't follow through on this procedure but I feel that it would be a solution for replacing the barrel.
It may also be possible to simply bore out the old barrel stub and thread it to hold a new barrel as well. Depending on how much material you had to work with.
It would probably be worthwhile to check with Steyr and see if they offer a rebarreling service at their factory.