I use a .450 Rigby Rimless on a Vektor double square bridge magnum Mauser tye action, weighing 10lbs fully loaded, 22 inch barrel. (Build by Gerrie Coetzee in Bloemfontein.)
My other 2 "big bores", that I have used occationally, or let clients use, are both M98 Mauser actioned custom rifles by Gerrie Coetzee, in calibers 9,3x64 and .404 Jefferey.