Getting a bit more into the technical aspect of the shackle and bolt. I agree that, as stated early, It's very surprising that MB didn't design a bolt with a shoulder that the nut was tightened up against. I've been a dreadful aviation hoarder/scavenger for years and have played with plenty of MB products. The innovative design and build quality is staggeringly impressive. So the use of a 'normal' off the shelf bolt is very surprising. (I know MB probably made the bolt specifically.
I am slightly puzzled about the torquing up of a locknut & bolt where you don't want the nut to bottom-out on the thread or even against a fitting the bolt goes through. In other words you are purely relying on the resistance to the 'locking' ability of the nut. A brand new nut is invariably going to be stiffer than a well worn one. How do you calculate a torque that caters for both cases? Clearly, if a normal nut were used you could only achieve a tightening torque when the nut is up against the fitting! If the specified tightening torque is less than the resistance of a worn nut screwed along a continuous thread, then you can only achieve that value when the nut impinges on something else.