Ever since their great nerf in Y2, lmgs just haven't felt worth using. My thoughts are give all LMGs a blanket 15% damage buff vs minors and a 10% buff vs majors. Then give exotic lmgs an additional 5% buff vs both minors and majors. Next fine tune the sub families a bit. So rapid fire gain an additional 5% buff vs minors. Adaptive remain unchanged. High impacts get an extra 5% vs majors and crits.