I know of four different methods to playing that barre chord. Two involve an individual finger and two involve three fingers.
Stephen Seifert uses his ring finger to lay across all strings. Aaron O'Rourke uses his pinky in the same way. Either of those methods require some practice as you have to build up muscles and callouses in your finger. They have the advantage of leaving your other fingers free to fret strings above the barre. People who play like that a lot sometimes get dulcimers with a radiused fretboard, meaning a fretboard that is slightly curved, making it easier to use a single finger to depress all strings.
The other methods involve either your index, middle and ring fingers on the bass, middle and melody strings, or your middle, ring, and pinky. I learned the first from Linda Brockinton and the second from Mark Gilston. Both have their advantages depending on the other chords and notes that follow and precede the barre. Most of the time I try to use my middle, ring, and pinky fingers on the bass, middle, and melody strings, as that leaves both the index finger and the thumb to play strings above the barre.
Any of these methods require some practice (the first two a lot more), so don't get discouraged if they feel awkward at first and if you can't get a clear sound right away. Keep practicing and you'll get it.
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Dusty T., Northern California
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As a musician, you have to keep one foot back in the past and one foot forward into the future.
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