The first person weapon position is controlled by
models/weapons2/shotgun/shotgun_hand.md3 or other
models/weapons2/x/x_hand.md3 for a specific weapons.
For development you can set cg_gunX, cg_gunY, and cg_gunZ cvars to offset the position. They are cheat protected so you need to load the map using
devmap command in the console.
Also please don’t edit posts to completely change the title/content.