My 4000 serial number series first generation Superposed trigger still works flawlessly. It is eighty years old and is a trigger that had a bad start and was "improved" in the mid thirties. The one in my gun never got the benefit of the "improvement". By the way, many conversions for light recoil operation are not really conversions to "mechanical" operation, but just a lightened inertia operation. Properly lightened 680 series Beretta triggers will dry fire successfully, but are still inertia in operation rather than true mechanical.