Shell Table - Synthlight/MHW-Editor GitHub Wiki
The values in the shell table are foreign keys referencing the rows in gunner_reload.gun_rd (reload) & gunner_shoot.gun_sd (recoil).
The Shell Type Id in Weapon Data references the index of this file.
M. Notation
If the reload or recoil you're looking at contains an "M" followed by numbers. Those numbers specify how reload or recoil can be reduced by customizing your bowgun with bowgun mods.
Example: 19 - Normal (Recoil +4) M1.2.4
In this instance, the string of numbers is how many bowgun mods are required to reduce the recoil of the bowgun using this recoil. The first mod will reduce it to Recoil +3, the second will reduce it to Recoil +2, and the fourth will reduce it to Recoil +1.
If there is no "M", then that specific recoil or reload CAN NOT be reduced.