How do Bates boots fit?

I already have a pair 10.5W USMC issue bates boots, but they do not fit. I am going to buy some more, but at $220 I want to make sure they fit right. In sneakers i wear an 11 and an 11 for sperry's. Now for my boots from REI i run a 12. I tried on an 11.5 D for bates boots, but they seemed a little too big. Does anyone think an 11D would be a good fit?