Don't mean to sound as harsh as this may but if whether or not "paintball" or pretty much any other particular extra-curricular activity, especially if it's not a varsity sport, is available in an organized fashion to you is a key factor in your decision as to whether or not attend a particular college, then USMMA, and likely any other Federal Service Academy, isn't going to be a place where you will be happy.
I'm not "dissing" your desire to continue to participate in this or any other extra - curricular activity. I am just saying that the culture, mentality of the rest of the student body at USMMA and/or the other Service Academies, as well as the reality that even if there is "paintball" or any other club sport today at USMMA - that doesn't mean it will be there next year given budget realities and fluctuating participation in such activities - all mean you may well find yourself in a place without organized access to the activity and among other young men and women who have differing values and priorities than yourself.