I am an accepted MD from this cycle. Wanted to comment to say that I did AmeriCorps during my gap year (currently still serving right now) and had to count it all as "projected" hours. I didn't talk about it too much in my secondaries since my program started in August, and I had my secondaries in by then. However, this was a huge topic during my interviews, and my interviewers all loved that I did AmeriCorps. I really felt like it did help me a lot once I got to the interview stage. Not sure how much it really helped me to get interviews though.
I also want to say that doing a service year is very challenging and the pay is quite literally awful. I only recommend to those who are very committed to the population they are serving because there are much easier/higher paying jobs out there. DM me if you want to talk more about it!!