Usually, "Paßkugeln" means roundshot (cannon balls).

But sometimes this word could denominate musket balls as well.

A "Paßkugel" is just a ball which matches the calibre with but very little ply; "passen" means: to fit in; "Kugel" is a ball.

"viele blieben durch Gewehrkugeln, Kartätschen und Passkugeln." - many were killed by musket balls, grapeshot and round shot.