I am no expert but it seems to me that being able to play a barre chord is much more a function of overall grip strength than just index finger strength.
If so, I would think that any of those grip-handle-squeezy-things (a technical term) would do the job.
Or you could just not play barre chords - I try not to. It's fun finding alternate voicings and so on. Of course I am a 95% fingerstyle player so, YMMV.
|