Like anything it all depends on how much he has to spend ,i would forget about a break action for a 577 ,FBWs Model L will do 577, but they havent been made for years ,and Leo Fix has sold all his actions ,The FBWs model S will do 585 Hubel, but i dont believe it will do 577 .Martini and Hagn action will do up to 600 on their Large Action but im think its around 3k ,just for the action .I started a Ruger No1 577 some years ago but sold it on to another shooter who completed it, and sold it for an exorbitant amount .But i now have a Ruger on a 585 Hubel which works just as well ,then there is all the other sky high European and English makers ,Jongmans in Australia who will make you one on their Farquarson action ,or Steve Szihn [spelling]who could make him one or that other gent that makes the double barrel Falling Block rifles in the U.S