A .460 Weatherby that started out as a .458 CZ 550. No brake and the only weight that has been added is that from bedding it. Full power loads with 500 and 600 grain bullets are pretty harsh. My uncle is in the process of buying a .577 Tyrannosaur. I fired a few rounds of 750 grain bullets at 2200 fps. Felt VERY powerful, quite a big shove. It should get real interesting when we start trying out hotter loads.