3 ms·I think it's possible to convert an M4 into its contemporary M16 and vice versa.by rangibaby 11y agoI think it's possible to convert an M4 into its contemporary M16 and vice versa.dsr_ 11y agoThe M16 entered service in 1963. The M4 is a derivative.rangibaby 11y agoI know that, but the M4 is based on the M16A2 from the 80s.