Recruiters are looking out for their assigned mission. They have jobs to fill and quotas to meet. Unless you're desperate, be patient until you get the MOS, bonus and contract you want. Don't let them badger you. Be honest. Be patient. Be firm. If you wait out the recruiter and don't give in to their pressure, you can get a better MOS. Don't just go for whatever they say. Research the job fields, find online forums to talk to Marines in various jobs, and find out what you really want to do.