155mm Lift
Chris had an L model and the lift was done with a USMC gun at Camp Lejeune. His weight and balance had him at around 22000 ( i.e., half fuel ). Your comments are correct re the sling limits: above 8K sling load has a max gross weight of 23,500 lbs.
He picked it up and did a vertical takeoff, said he had a very decent vertical climb at the 120% Q limit. Flew it around awhile and returned it to place. It was a demo, not a data exercise.
Actually high density loads like guns usually fly quite well, and relatively fast. Its the high volume, low density loads that tend to want to fly their own flight path.
Thanks,
John Dixson