The data comes from the Veritable Records of the Joseon Dynasty. https://sillok.history.go.kr/intro/english.do I'm browsing it. Wow, there's so much detail, like:

己酉二月, 世宗講武于平康, 世祖射鹿, 七發皆貫其項。

기유년 2월에 세종이 평강(平康)에서 강무(講武)를 하였는데, 세조가 사슴을 쏜 7발(發)이 모두 그 목을 관통하였다.

"In the second lunar month of the giyu year, King Sejong held a military drill (gangmu) at Pyeonggang. Sejo shot seven arrows at a deer, and all of them pierced its neck." https://sillok.history.go.kr/id/kga_000002

Many K-drama and movies are inspired by these records.