This is a great historical and useful website for the Art and Science of Machinegunnery. The art of machinegunning reached its height at the end of WWI, and this website has all the Vickers machine gun manuals, papers, Technical papers on how to employ a machine gun to support offensive and defensive fires to include indirect fire with a machine gun. They also cover barrage fire with massed machine guns firing at the same targets.
I know there are all kinds of other weapons for support but as an SF operator, you can find yourself in a situation where the only thing you have is your MGs.
https://vickersmg.blog
For you military history buffs it has great information.
Search for this video on the site that will not be named. It demonstrates solid basics on the employment of the MG.
Employment of Heavy Machine Guns in the Attack - 1944