Joe,
If you click on my profile you will find the album on the right side of the page. The photos are from an Ithaca Lewis model. There exist a few differences between Crass and Lewis, but most Lewis parts will work on a Crass model.
You can check Numrich for parts under "Crass Hammerless" (
http://www.gunpartscorp.com/Manufact...tm?results=All), or the Ithaca Lovers forum on shotgunworld.com may be of some help. Numrich doesn't have an extractor, but they do have firing pins and fp retaining screws.
Both other parts you are missing include springs. I'm sorry to say that I did not dimension the barrel lump pieces, so can't help you there.
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