RE: CVA Opima Magnum ?
Joe, whoever you got the CVA from should have given you a breech plug wrench with it. It is a two piece wrench; one part approximately 6 inches long which fits on the plug and another piece approximately 6 inches long which is just a solid rod to use for leverage to break it open. If all else fails you can go to CVA's website and order a replacement wrench set.