Remember that however lenient UA may be, LH or UA-codeshares on LH are subject to the strict 8kg limit--most of the time. It may be randomly enforced, but it has been enforced on every LH TATL flight I've been on in the past few years.
No one has raised questions on lifting this bag up for TSA inspection--I was once queried on a carryon at BDL because I had about $10 in quarters in the bag. 100 lbs of coins might trigger some mild curiosity from a TSA screener.
Flyer 420
in Seattle