Ruger actually did chamber the WSM's for a while but I heard that they had to pay some sort of royalty to Winchester/Olin for it and got tired of paying it so they quit. Not sure how true thatis but that's what a I heard. Bigedp51, I understand what you're saying about an oiled chamber or cartridge and understand what bolt thrust is and don't doubt your knowledge. I also know/agree that a larger diameter cartridge puts more thrust against the bolt face. I myself do not do anything to tempt fate either and am always careful with my firearms. However, in the quote you posted it says that an oily chamber can increase the pressure to the bolt face to the equivalent of 70K psi which isn't enough to make the bolt action fail unless it has a major defect in the metal that wasn't found at the factory. All bolt actions are capable of withstanding at least 120K psi and I've read some quotes that claim they can withstand 150K so I wouldn't worry about 70K. Like I said before, Norma loads the Weatherby rounds at around 70-75K, pushing the limits of the what the web of the case can handle. Back to the original question, if you wanted a 270WSM you'd need to have a new barrel made. The existing 270win barrel chamber would have to have too much cut off to rechamber and the taper of the barrel would cause the chamber to be too thin.