I may want to rename the "AddGun" to something else better, considering the term of "gun" is not okay for Mojang apparently -even though they're very selectively enforced- so to play safe, I will have to rename the plugin. Besides the "AddGun" is named after a popular demand and even memes from DevotedMC community simply by saying "add gun" repeatedly. It's not a good plugin name to be honest, definitely could be named better than that.
Will come back to this after improving and fixing bugs.
Currently the inventory gui in /giveselfgun, /giveselfbullet, and /giveselfmagazine commands do not refresh every time you pick up a item from the item list menu. The intended behavior is whenever you pick up a item from there, a new item should appear every time you pick up and put in your inventory.