I had to do the same thing with my barrel to make them fit the Renegade. They will not replace the barrel. In the bolster were the nipple goes in, I was told that they had a tap which left rounded edged threads instead of a sharp crisp cut thread and that they replaced the bolster and then send it back...

You're really going to like the way the rifle shoots. My three Green Mountain Barrels shoot excellent although one is a smoothbore and after 50 yards your on your own for what I consider real accuracy...