Yeah, it's to bad about not getting a combat arms MOS. One of the perils of going "open contract." You can try for a lateral move, and I would reccomend it, but it is difficult to do before it's time to renlist.
Or, if you want to live dangerously, fail out of your MOS school and they might send you to the infantry. I don't know if this really works, and if it did you would have a black mark on your record.
I repeat: This may be an urban legend, you might get a discharge if you fail out of a school. Somebody of more recent vintage help me out here.
You might "request mast," going as high up the chain of command as you are allowed, respectfully explaining to the various officers your burning desire to be a grunt. This approach will take some guts, because everybody will try to dissuade you. But it is your right as a Marine to take problems up the chain of command.
Of course, there will come a point where the buck stops, and the Regimental Commander says "no." At this point, you will have to come to attention, give the proper salutation, about face, and leave his office...and that will be that. Nothing to do but suck it up for your first enlistment.
But most high ranking officers are or were grunts at one time. So they will understand your motivation. Don't lie. But make your case in a forceful but respectful manner. No whining or crying.
You might get lucky. They might have an opening in the infantry. They might have an "over supply" of supply guys.
Do this early. When you report to the School of Infantry for your Basic Warrior Training would be a good time. Especially since your officers will all be grunts.
But lose your fear of officers and NCO's. they are guys, just like you. Don't be afraid to speak your mind, but do it respectfully, with tact, and never in a whining, complaining voice.
The Marines are about mutual respect. You respect your officers as men, and for their superior skills and knowlege. They respect you as a man, and because you are doing the "grunt work," learning skills, and making them and the whole Corps look good. This is how it's supposed to work.
I went open contract myself, being young and dumb, and became a tanker (1811) which was OK. Definently combat arms, and tanks are pretty cool. But I renlisted after 3 years for the infantry.