Need help with 1917 model rifle

[Spiritwalker]

A remington rifle has been passed down from my father in law to my son and we are having a problem identifying it. It's serial # is 39312 & it says model 1917. We think it might be a 30A or a model 30 express. We don't know what kind of ammo it uses and we need to buy an ejector spring assembly and a couple of screws for it. It's also missing it's rear sight. Can anyone help us with a positive ID and where to find parts? Thank you!