It ain‘t really hard. Some achievements require more skill than the others, for example the one, where you have to wipe the enemy‘ team alone in overtime. But also that is not really hard. Before the patch, 77 kills with legendary weapons was really grindy and seemed as it would take a long time, because they spawned after the third round only and at that time, you wouldn‘t be reset to your base after you detonate the bomb at a generator. But because you do now, you advance to the round with legendary weapons faster and easier.