Reading them tells you that Sō Yoshitoshi, the daimyo of Tsushima, presented the Korean court in April of 1590 with the parting gifts of two peacocks, a spear, a sword, and the first musket to come into Korean possession. The Sō family is highly interesting.
The question is what if Koreans replicated Yoshitoshi's gun and had some of them in reserve before 1592 invasion of Korea (or during and after the Imjin War) ?