Halo 3 hit detection issues explained, also apply to Halo 2 and Halo Reach
in the latest blog
If I understood this correctly:
In Halo 3, in first two ticks at 60Hz, bullet would travel for 3wu hit scan + 3wu travel + 3wu travel = 9wu.
In Legacy Halo 3, in a single, first tick which is the same amount of time as two ticks at 60fps, bullet would travel for 6wu hit scan + 6wu travel = 12wu.
First four ticks at 60 Hz = 15wu, first two ticks at 30Hz =18wu. It is 3wu behind at all times.
This is the reason why increasing bullet velocity in 60fps Halo 2 Vista and 60fps MCC Halo 3 makes hit detection closer to Xbox versions.
Just lead your shots 4Head in Twitch chat was actually not shitposting, it was a wise advice due to MCC weapons being effectively slower compared to Xbox 360 versions.
This is not the only issue with hit detection in Halo 3, there are some issues still there that were fixed for Xbox 360 Reach and will be backported to Halo 3.