I spent Christmas with my family in Florida. My grandfather and I got to talking about shotguns, and he told me that he had a shotgun that had belonged to my other grandfather (long story). He took it out and it turned out to be a Remington Model 17. He told me it was mine when I wanted it. (As I was flying home, I didn't decide to take it with me.)

My grandfather told me it can't be fired anymore as it was designed for use with paper cartridges. Is this correct?

The Remington Model 17 is a John Browning design. It is bottom ejection. If in good shape it is a great shotgun.i can see no problem shooting modern plastic shells in it unless it has a short chamber-less than 2.75 inches. The Ithaca Model 37 is a take-off on this Browning design.

The Remington 17 was produced by Remington from 1917 to 1929, I believe, in 20 gauge only...After that, the patent was bought by Ithaca and became the famous Ithaca M 37, with a few minor changes..

I have a Rem 17... My Dad bought it used back around 1950 for $35 and it it still in excellent condition....It is perfectly safe to fire with any standard 2 3/4" 20 gauge factory loads, including foster type rifled slug loads.....I don't know about some of of the fancy steel alternative or modern alternativeslug loads, but it is fine to shoot with any standard modern plastic shotshells loaded with lead shot..