So with this it is a really grey area as to what you should do.
You go onto any call of duty game, even the latest ones taht come out like for example Warzone, you have tones of campers that camp on roofs etc. So i can understand the fustration from that point.
However with the M21 being rather overpowered if that is the case, then this will have to be investiaged. I must admit, i have not played on the Hardcore server for a while due to irl commitments. But if it is being abused with camping, @RedRose suggested something really simple which i don't see as bad thing at all personally:
Simple things can change actions of people. I would most certainly hesitate from jumping streight to a warning, as fustrating as it can be, as it happens in all games with camping. But if the M21 is at a unfair advantage, then fair enough, investigations can happen.
As said though, i have not played for a long while so please do advise.
Hope we can come to a understanding as, im sure you will agree, IceOps has a lovely Family and Communtiy.
Disagreements are not a regular for us