When you begin modifying the design of a gun, you have entered what they call gunsmithing, which is part art and part science. Don't expect someone to be waiting for your call with a package of parts to perform that modification.
This general topic is of interest to many shotgun owners who have become tired of having their hulls launched when they open the gun. While each manufacturer does it a little differently, o/u ejectors all work pretty much the same way. There is an ejector hammer and an ejector sear which is tripped during opening. The ejector hammer (and ejector hammer spring) smack your ejector tangs and launch the hull.
You can completely disable the ejector system by just pulling the ejector hammer and ejector hammer spring out of the gun. Or you can put in weak springs which will just pop the hull back similar to a real extractor system. Usually, an ejector system is not easily converted to a true extractor system, but the results of using weak ejector springs accomplish the same thing. Once your heavy duty ejector spring(s) are out of the gun and you can actually see the mechanical arrangement you are modifying, then you can measure the dimensions of your springs and go hunting about at the local gun show for something a bit lighter. That might take some time, or you might get lucky and find something during the first hour or two. You may find the right diameter spring, with weaker wire, but it will need to be shortened. That is where the artistic ability kicks in. YOU are now the designer of your new ejector system. In one particular case, I found that cutting down 1911 firing pin springs worked just fine in a Franchi o/u. Some experimenting is usually needed. Also, Wolff sells a big "general assortment" of misc. springs that come in handy for just this type of thing..
In general, it is not necessary to order special parts from the factory or file on metal parts to get this system to work properly. Just some patience and a good set of screwdrivers.
-Lazarus