This Saturday, October 5, there will be a discussion of 5 musket balls recently discovered (2023) on the east side of North Bridge. That is the side of the bridge where the British Regulars were formed up on April 19, 1775 indicating that they were fired by the militia on the west side (Col. James Barrett, Major John Buttrick, Captain Issac Davis, et al.).
Archeology Day (https://www.nps.gov/mima/planyourvisit/special-event.htm)
Collectively, those musket balls might be considered part of the actual "Shot Heard 'Round the World" as described in Ralph Waldo Emerson's 1837 "Concord Hymn."
The calibers of the musket balls range as follows:
.650
.70
.568
.655
.41
The ball were largely un-deformed, so they likely were overshot, reached terminal velocity, and dropped to the ground.
More detailed information may be found on this page:
Musket Ball Discovery (https://www.nps.gov/mima/learn/historyculture/north-bridge-musket-ball-discovery.htm)