yeah, ts a new thing that is being implemented in most new games. I promise you, you get used to it quickerly
If you mean the real machine-gun (e.g. eg42) then you can only relly fire properly if you deploy it (by going prone and left clicking) or finding somewhere whewre you can deploy it in the maps (on top of sandbags e.t.c.). A little icon appears if you are in a place where you can deploy the machine gun still standing.
With other weapons, you get used to the recoils after a few days of playing. You reduce it a bit by crouching and going prone
Hope this helps