Banjo B♭ chord (Double C)B♭ major on the 5-string banjo: 2 3 2 3, and 3 more shapes

Frets, string 4 to string 1: 2 3 2 3 (first position)

1. String 4 (C): 2nd fret, index finger (barre), D
2. String 3 (G): 3rd fret, middle finger, B♭
3. String 2 (C): 2nd fret, index finger (barre), D
4. String 1 (D): 3rd fret, ring finger, F
5. String 5, the short g: open, G, not in the chord

Sounds: D B♭ D F  ·  B♭ is B♭, D, F (1 · 3 · 5)

Found in: C mixolydian (♭VII), G dorian (♭III), C dorian (♭VII), G minor (♭III), D minor (♭VI), C minor (♭VII)

The 5th string: the short g adds the 6th over B♭, a colour rather than a clash.

Double C tuning: gCGCD, the short 5th string first, then strings 4 to 1.