I built one of these several years ago. 1-14 twist barrel. I still have the dies and some brass, but I can tell you that the barrel had to be set back at approx. 350 rounds. At approx. 600 rounds it was done. I put a second barrel on it, and it lasted about the same.
It was a laser to approx. 600 yards if they bullet didn't blow up with was a major issue with it. Harvested quite a few coyotes with it but it was expensive to shoot due to barrel life. I think I still have the paper article that came with the rifle describing it's development?