Hi Rod,
Do you want the old model mid size frame, new model Flat Top Blackhawk mid size frame, or new model large frame? Here's averages for all three:
Cylinder (body) Length
Mid Frame
Old Model
.357
Blackhawk
FT and 1962-72
Ribbed sight frame = 1.602"
Mid Frame
New Models: New
Vaquero and
FT BHs = 1.610"
Large frame New & Old models:
Original Vaquero/
Blackhawk/
Super BHs/BHs = 1.642"