Yes,I have a early H.Holland .450 BPE that suffered greatly in India.The pin and hook were both worn,built the pin up with tig and lathe turned it,as well as the hook.The screw,(or drum)also had worn spot that was built back up with weld,and finally the bolt,(lugs on barrels)were also rebuilt and fitted.If your barrels are on face and the under lever travels to far --it's worn.
I tend to think with proper cleaning and lube, the Jones under lever would be difficult to wear out.