Answer:
Yes- BUT- in an autoloader, they may not cycle the action. In a lever action, they may not feed properly (too short). In ANY rifle, be certain to clean the chamber well after shooting- you will get a buildup of carbon in front of the case mouth that can make chambering Magnums hard if you don't. Also, if you have a gas operated auto, like the Ruger, remember that Ruger recommends you NOT shoot unjacketed lead bullets (gas port fouling)