What S.P.E.C.I.A.L increases the damage of Gauss Minigun?

As the description hints, what S.P.E.C.I.A.L-points increases damage of the Gauss Minigun? I have googled a lot and as i understand it, Heavy Guns get extra damage from End while Ballistic and Energy gets extra from Int. So, do i get extra damage from investing points in both End and Int or am i way off on my guess here?