If a certain playstyle or gun isn't working, e.g being aggressive with a Shotgun. Then you switch to something that does work like the LMG, it's best to stick to what's working well vs the enemy.
Plenty of matches I've started with the intention of using a battle rifle or something. When it's not working or I'm dying more than I like, they will start crying when I whip out the AK74u.
I just see it as a "Oh well you asked for it buddy".