I really think the Mini Gun needs some love in Fallout 4. It's such a big and powerful looking weapon, yet it doesn't really dish out much damage, it's embarrasingly underpowered late in the game infact, esp. compared to its laser counterpart the Laser Gatling.
Therefore I believe would be extremely awesome if in a patch or DLC we were given the ability to upgrade the Mini Gun's caliber/reciever the same way as with other weapons: That way you could upgrade the standard Mini Gun to do the same in ballistic damage shot for shot as the Gatling Laser does in burning damage, finally providing us fans with that powerful Mini Gun we're all striving for.