They are really popular because of the lvl 1-2 vixens on Rocktropia. So what you do is go outside club neverdie where they are packed DENSE, u wear no armor and just auto shoot the thing at the ground. It will ALWAYS hit for max damage because it has to do atleast 1 damage to all it hits and it hits 10 vixens in this area because of how dense they are. Then you are getting two things, grenadier exp and also pretty good evade exp. Explosive ammo is cheap and to do this all you need are the Launcher, and a fapper. Just a really cheap way of skilling because the vixen gears are about 800% MU. I think you actually turn a small profit (5 PED hour or something like that) doing it this way.