Wested's Off the Rack Sizes?

[Castor Dioscuri]

Out of curiousity, does anyone know what chest sizes are Wested's 'Small', 'Medium', and 'Large'?

I'm thinking of ordering a LC jacket, but am not too sure on getting a custom fit... Some of the photos here make a custom fitted jacket seem to fit the wearer too well, while in the Indiana Jones movies, it seemed to me that Harrison's jacket looked a size or two too big for him, like an off the rack jacket as opposed to a form fitting one.