Krakow , the under lever dose not have any mechanism that locks it up to give the "click" you mention. However this was achieved by some makers, by having a small ramp on the edge of the trigger guard over which the lever ran that acted as a "lock" . Over the years these can ware away or have been polished off with overzealous restoration .
There have been thousands of guns made withe this type of lever and some makers continued to use it on heavy weight big bore s as well as heavy caliber rifles ,they come in all qualities from the very well made to the plain awful so like any device or mechanism there can be no one solution to any given problem . Due to the amount of time that is needed to do the job correctly and not forgetting that 50/60 years ago we did not have the welding techniques we have to day many repairs were made on the cheap [ old gun not worth much ,don't want to spend a lot ] .If I had a pound for every time I'd heard that !
