Indeed. The actual change in recoil strength and reload time is not entirely dependent on the Recoil Down and Reload Speed skills, but also dependent on a hidden specification for each weapon, which is somewhat unique to each bowgun, ammo type, and ammo magazine size. The skills improve the hidden specification value, and then determines whether the weapon has reached a threshold for a particular recoil strength or reload speed, then uses that threshold as the final recoil strength or reload speed.
For example, assume that the threshold value for “Average” recoil is 40-59. An ammo magazine with innate recoil strength of 40 and another ammo magazine with a recoil of 55 will both have “Average” recoil strength. Assuming that Recoil Down Lv. 1 reduces the recoil by 10. The first magazine will go below 40, and becomes “Low” recoil, while the latter magazine will have its recoil reduced to 45, which remains as “Average”.
It is similar to how the Guard skill does not work the same way for all types of shield against the same attack from a monster.