I stash away the strongest weapon of each element for use as a primary weapon. I never use SSR weapons as fodder. There's enough SR weapon fodder with useless skills that for now I'm also holding onto fully LB'd off-element SR assault weapons. Keep in mind, however, that an SSR weapon that isn't LB'd at least once (and you won't be able to obtain more copies of from a Renewal event) is more or less useless as a secondary in the long-term.