While watching Raiders, it seems that the collar size differs from scene.
In some scenes, for example The Raven-Bar scene, it looks kinda small, and not like the current wested standard.
I think you may be one of the last to nitice this.
Seriously, all you have to do is ask Wested to make the collar whatever size you want and they will do it up for you. I have mine at 2 1/4". I think smaller is more Raidersesque.