Maybe. Other rifles have 30-round mags though.Again we're assuming that the semi-automatic Rifle was an AR-15 or AK47 variant, one even assumed an FRT was in place...I'll even speculate that it could be done with either, but not easily certainly would take time to cool the barrel and swap magazines, even Belt fed are generally <=250 rounds at a time.
I've got 60 rounders and drums for mine. Just saying....Maybe. Other rifles have 30-round mags though.