Thanks Scott and Bob.
I don't think I want to mess with the original barrels, being that it's a family gun. Someday I'll probably just get a replacement barrel with the Rem-chokes so it's infinitely adjustable. I'll save the Full and Skeet barrels for trap and skeet shooting. If I can get a duck load to pattern decently with the skeet barrel, then I won't be in as much of a hurry to buy a barrel.
Thanks for showing the pictures of the parts. The other day my father in law showed me how to load/unload the gun. Then we switched the barrels over. In preparation for some sporting clays today, I tried to load it and fire it yesterday afternoon. I couldn't get a shell in the magazine and I also couldn't get the trigger to pull back. I wanted Ben to practice with it and so I brought it to the club today anyway. A friend looked at it and found an extra set of rings stuck up inside the collar on the skeet barrel. He removed them and the gun worked fine. The o-ring does look pretty worn so I'll probably be buying one of those soon. I spoke to my father in law and he said that a couple of years ago he switched the barrels from skeet to full and thought he had lost a ring. Not knowing it was stuck on the skeet barrel, he bought a replacement ring and put it on the gun.
Ben did well with the gun today, busting more clays than I did. That's great shooting for him compared to how he was shooting last year.