I have looked everywhere, but have been unable to find instructions for re-assembling the breech bolt for my Model 820b shotgun. Specifically, the 2 extractors are different from one another, and so are the extractor plungers. I ordered all new parts from Numrich, but the parts diagram on their website does not definitively identify which is left and which is right, and the parts arrived in unmarked bags. Any help will be greatly appreciated...Angelo.