Originally Posted by: faith83

If I lift my ring finger and play an open G string on a 5th string barre chord, does that turn the barre chord into a 7th in the same way that an open G turns A into A7?

[p]If you mean what I think you mean, then yes. But, assuming you mean this A major shaped barre chord, with this fingering.

|--5--(i)----|

|--7--(p)---|

|--7--(r)----|

|--7--(m)--|

|--5--(i)----|

|------------|

Lifting your ring finger would cause the G string to ring at the 5th fret and that would be a minor 7th in relation to the root note, resulting in a dominant 7th chord.

|--5--(i)----|

|--7--(p)---|

|--5--(i)----|

|--7--(m)--|

|--5--(i)----|

|------------|

Chord tones:

|--5--(5)---|

|--7--(3)---|

|--5--(7)---|

|--7--(5)---|

|--5--(1)---|

|------------|

I cover the basics of movable dominant 7th chords in this tutorial.

https://www.guitartricks.com/tutorial.php?input=499

Hope this helps!