I\'ve only actually seen it on our manuals, like the 1C-130(H)H-2-11.
I can\'t find anything that specifiaclly says so, but maybe since all manuals start with the 1C-130, the decided to move the H part of the HC-130 models after the number.
This book covers:
RADIO COMMUNICATIONS AND NAVIGATION SYSTEMS
USAF SERIES
C-130E, EC-130H, HC-130H, HC-130N, HC-130P,
MC-130P, NC-130H, AND WC-130H
AIRPLANES