6" hsb with 3-4" panfish....here's some info Bill Cody posted here http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=372409

Here is my contribution for this project:
HSB Gape Information
Total length then Gape Width.
5.5" gape 0.59" (15mm)
9.75" gape 0.94" (24mm)
13.5" gape 1.1" (28mm)
19.0" gape 1.73" (44mm)
22.0" gape 2.1" (55mm)

Here are some data that I have for SMBass.
Total Lgn Gape Width
5.5" gape 0.71" (18mm)
9.5" gape 1.1" (28mm)
13.5" gape 1.57" (40mm)
17.0" gape 2.3" (58mm)

Here are some of my data for LMBass
Lgn Gape Width

5.5" Gape 0.83" (21mm)
9.5" gape 1.5" (39mm)
12.75" gape 2.0" (51mm)
17.0" gape 3.9" (100mm)

Mat Peirce
1.25 acre southeast Iowa pond
LMB, BG, YP, WE, HSB, RES, BCP