How difficult is it to reclassify during RSP?

You may want to contact your recruiter to find out for sure, but if you've already sworn in and signed the dotted line then it may not be that easy. Units have slots for jobs they need to fill, and recruiters (MEPs personnel) can see which slots are open. When you signed up and were place in a unit and took up a slot. If I were you, I'd contact the recruiter or even the unit you're going to and ask them yourself. I've never had to deal with anything like this so I'm not 100% sure if its possible or not. I don't see why you couldn't switch if there was an open slot though.

There is a drastic difference between this two military occupation specialties, are you sure that 11B is what you really want? Take it from an Infantry soldier that could have picked anything, this is a big choice, and you may regret it later. I'm good with my choice, most of us are, but it is The most competitive MOS in the ARMY, and basic at Ft. Benning is just the first stop of many. Are you up to the challenge of AIRBORNE, AIR ASSAULT, RANGER, SF, and all the other specialty schools that you could attend on your path to a stellar career, it do you just want to be a grunt, and are you certain you are aware of all that being either of those entails. Good luck, and welcome to your commitment to being your best!

Which infantry unit are you trying to join?