I don't know anything about their pulling collars, but I have a Billy Cook headstall with tooling and I think it's one of the prettiest headstalls I've ever owned. The leather is fantastic quality.
Yes, I believe they are made in the USA (I would be surprised if they weren't). I know they have a manufacturing place in Sulpher, OK. There is also a Greenville, TX version of Billy Cook saddles. And to be honest, I just assume mine is an Oklahoma version. (I don't know if the Texas versions are just saddles of it they label other Billy Cook tack). But at any rate, I doubt you would be disappointed in their breast collar. The place I bought my headstall had more of their headstalls and breast collars and they were all beautiful quality. Really nice leather. Nice tooling. I love mine.