[Harp-L] Solder retune - practical limits?

[Blunt White <playharp@xxxxxxxxxxx>]

A professional guitar playing friend is learning harmonica (plays in first position, G harp), he has problems with blowing out blow note 7 (I've explained why no bending down on blow 7).  My last repair used a replacement reed from a Bb harp tuned down 1.5 steps with solder.   This replacement retuning scheme was based on measuring reed thickness near the rivet end, the Bb replacement reed was significantly thicker than the G reed.   The result seemed to last longer.  This time I'm going to replace G blow reed 7 with a blow reed 7 from a C harp, a drop of 3 steps with solder (a bigger hammer).   Seems like a big drop?   
 
Interested in your thinking.
 
All the best,
Blunt White
Stonington, CT USA