Originally Posted by
Tracklet
Yes, you can board any unreserved Capitol Corridor train with a reserved California Zephyr ticket without having to exchange the ticket. I used to purchase reserved "weekly specials" tickets for the CZ and use them on the unreserved CC trains to commute - it was much cheaper than purchasing a 10-ride ticket!
As the reserved train is the one with the most restrictions, riding an unreserved train in the same corridor with a ticket for the reserved train should always work...especially since Amtrak train crews are typically happy to accept virtually any piece of paper.
One interesting angle on this was purchasing a Coast Starlight ticket and riding the CA regional Amtrak on the south coast...and then claiming the 500 Alaska miles, rather than the 150 AS miles normally due.