Hi romer12, yes, they can go for quite awhile, and some will probably never fail... but they seem to do it at the worst possible time! ..
... Mec-Gar mags suffer somewhat form this same affliction... I have replaced many bottoms in both types, and the much stronger spring in the Mauser type mags sure doesn't help the weakened plastic bottoms any.. For shooting, Aluminum bottoms, or Swiss Bakelite bottoms would be my first and second choice.. Good dense solid walnut is satisfactory, but not nearly as strong as the aluminum...
... Best to you, til...lat'r...GT