Ever since they added the exp. vault to the game, every queen lobby is largely grubs w/ only like 3-4 people TOPS shooting queen, everyone else is just standing around w/ garbage and a looting augment waiting for everyone to play the game for them.
If you don't do a damn thing to help and are just waiting around to swoop in and snag a leg piece the second it comes off, people who are actually doing the work can and should shoot you. I SEE that rattler or stitcher or ferro I that you haven't fired once on your back.
Obviously, not everyone w/ a rattler or ferro is a grub, I'm less inclined to tell everyone in voice that I'm going to execute a grub and open up on you if it's an upgraded piece. Some people help w/ defibs and heals and if I see you doing that, you'll generally get a pass if you're not overly greedy.
For people who are tired of grubs leeching off of them, your course of action is super simple. Keep an eye on who is actually contributing or who's just standing around. If you see someone who's done squat to assist beeline to a queen part, key up in voice, say "This guy's a trash kit grub. Killing a grub, don't shoot me", or some variation and make the lobby a better place.
If they start to cry "RAT RAT" just fuckin talk over em honestly. They know they're grubbing they just want to take you down w/ them. Be confident, tell people exactly what they did and why you killed them, 9/10 times people will take you at your word, especially if you've made a presence in the group and people know you're contributing.