Last time I checked they had FM field manuals and more tactical documents in their download section. Asking in the forum also can link you to guys being in the knowledge and owning such material. I remember that several of them posted digital copies of this and that.
Edit:
http://www.steelbeasts.com/Downloads/p13_sectionid/19
18 Army FMs, 8 Marines FMs, 39 Russian manuals. Sleep well.