There are a couple of ways to do B maj. Depending on the situation, you can use whichever is most comfortable.
One of the first things I was ever told was to make chords with as few fingers as possible so that more fingers were left for adding extra notes, etc. Thus I normally make a B maj with index on the 2nd fret bar(re) and use my ring finger to bar the d, g & b strings at the 4th fret. But it is hard to not muffle the E string that way because my finger just does not bend backwards enough, so I will use variations when I need to.
...so ever since then, I always hang on to the buckle.