Many Company of Heroes 2 players make the mistake of considering the HMG more of a defensive weapon that should be used to cover an area but in reality, these weapons are most powerful while they are mobile.
Suppose you have a Pioneer squad trying to capture a point and some squads attack them. What are you supposed to do then? Having an HMG to back up your Pioneers while they capture the point is a good idea as it will enable you to suppress the enemy attacks.
If you have forced an enemy squad to ‘Retreat’ with an HMG and have no other enemy troops in your line of sight, then this is the best opportunity to advance or change the position of your HMG.
Like I have mentioned before that it is a good idea to keep your HMG mobile as it will allow you to avoid mortar fires or enemy flanking it and thus preventing it to get destroyed. It also confuses your enemies as to where your HMG will be, and they will think twice before entering your territory.
One of the most amazing things to do with an HMG in the beginning of a game is to determine from where your enemy is most likely to attack and position your HMG in that area. Most of the experienced players I have known have this innate ability.
However, it is a good idea to back up your HMG with a few other squads. I would advise you to use MG Bunkers for defense and HMGs as fire support.
While confronting a light vehicle, HMGs alone can’t do anything. So it always better to have them backed up by AT Guns or Panzerfausts. The German MG-42 work like a charm in these kinds of situations and it can be activated while being garrisoned in a building.
While garrisoned in a building, you should only worry about vehicles with flamethrowers. Otherwise, your HMGs will always win no matter for how long the enemy vehicle exchanges fires.
Also note that, MG-42 can easily be crushed and can be destroyed by vehicles like Ostwind, Panzer 4, T-34 or T-70.
Placing an HMG
The worst you can do while placing a HMG is when it faces hindrances in the line of sight and can be easily flanked by enemy troops.
A good position for a HMG would be to have a clear field of fire while an excellent way to position it would be to place it in a good cover or place it in such a way that it is covered by areas which enemy forces are unable to cross and the only way they can reach it would intersect with the line of fire.