I sampled a 0.36 ac pond and caught 3 LMB. Mouth gape was:
10.75" gape 1 11/16"(43mm)
11.5" gape 1 7/8"(48mm)
11.75" gape 1 15/16"(49mm)

Also interesting - the HBG has a mouth gape twice that of a bluegill.
Bluegill 8.25" gape 5/8" (16mm)
HyBluegill 8.25" gape 1.25"(32mm)


aka Pond Doctor & Dr. Perca Read Pond Boss Magazine -
America's Journal of Pond Management