MG must be defensive and area denying tool not offensive. Offensive MG it's LMG or guntrack with quads. Main problem with maxim it's that core infantry of SU - conscripts are too weak in comparsion to grens and volks, that was a reason to build only maxim's instead cons. But IMO penals are good, with AT satchels they can fully replace cons as core infantry (it's weird because penals are "elite"), their AI capabilities are pretty solid (without PTRS guns). Also they very good for late game phase where cons absolutely trash. For more aggresive offensive try to use shocks.
Maxim was made to be an offensive weapon.
Shocks are doctrinal are too short ranged.