features (3.x ~ 6.x):

3.x is prepared for classic TaC, while 4.x is made for TaC Zero.
5.x is prepared for ShoulderSurfing 4.
6.x is prepared for ShoulderSurfing 5.
(3.1+ only, not incluede in 4.x or 5.x) Dynamic aim mode: tap aim button to switch between FPP+ADS/TPP+Hip-Fire
Registers guns (when aiming) as ShoulderSurfing adaptive items
Aim down shoot will zoom in third person mode.
(4.x) Makes recoil work in shoulder surfing mode.
(6.x) Guns are compatible with free looking functionality from ShoulderSurfing 5.

2.x features (intergrated in ShoulderSurfing 3)

Make player rotation only synchronize with camera rotation when aiming/using item, enables viewing your player model from front in third person mode.
Remove second person view and vanilla third person view, which is somehow redundant with this mod. This makes perspective switching more fluent (only 2 modes remaining).
It makes guns shoot towards where the crosshair points, instead of the player entity's view vector

FAQ

Q: 1.16.5?

A: No, Downgrading to MC1.16.5 will also downgrade Java version from 17 to 8, which is too frustrating for me

Q: What about the 1.16.5 version on github?

A: Someone paid me for this, but not further updates.

Q: Arclight is crashing

A: Both this mod and ShoulderSurfing are CLIENT ONLY, and should not be installed on dedicated servers.
Arclight running from shell scripts IS a type of dedicated server.

Screenshots