I definitely partied in undergrad (mostly on the weekends), BUT I cannot fault the OP. He was trying to sleep. That's why I usually took my parties off campus. Fortunately, I had a lot of friends who either had off-campus places or had friends that KNEW someone who lived off campus.
But whenever we drank in the dorms, we usually were smart enough to keep the noise down so as not to draw attention. But we were usually just pregaming in the dorms (like around 10pm or 11pm....not at 2am or 3am). I honestly can't think of too many times when we were just drinking in the dorms without the intent to go out to another place....especially if we were pretty loud.
In my experience, 2am is usually when everyone was coming back to the dorms. Things still might be a little loud, but we usually weren't still drinking at this point.
But I suppose the OP should have asked them to keep it down instead of going directly to the RA. When I was living in a super small dorm, I had to ask my neighbor to turn his TV down (because he would watch movies with his door open) and once, my neighbor asked me and my roommates to turn our music down because she was trying to sleep. No harm, no foul.