I've never heard that about turning a fired barrel. I do know that barrels can get longer while being turned, as they heat up during the process, and if the guy running the lathe doesn't keep that in mind, they can warp.

Looking at the Verguerio next to a standard 98 Mauser action it appears the triggers are identical. So, any adjustable 98 trigger group ought to work on the Verguerio. M98 trigger guards will interchange. I think these features will let the Verguerio make into a really nice rifle.