Based on this video, I heard only 17 cannon shots. https://www.youtube.com/watch?v=ZwvbQR887W0&t=8h12m15s Base on screen shots of the rounds magazine before and of the last scene I counted 19 missing rounds. Two rounds are in each of the loader's hands. Did Biden only get 17 gun salute? According to this document: https://armypubs.army.mil/epubs/DR_pubs/DR_a/pdf/web/ARN20654_R600_25_Admin_FINAL.pdf That's:

Governors of a territory of foreign possession within the limits of their jurisdiction or American ambassadors having returned to the United States on official business Interesting.

In this video I only counted 11 https://www.youtube.com/watch?v=UIprRLYcteA&feature=youtu.be