I believe the Lazzeroni's just like the WSM calibers have too much bolt thrust to be chambered in the TC Encore. You can read a little about this on eabco.com. These guys make Encore barrels in a lot of calibers that TC doesn't. They don't make them in WSM chamberings because of the thrust issue. You cannot get the Remington ultra mags either. You have to choose between the 300 Win. mag or the 300 Weatherby.