Sorry I haven't been around to reply in a while. I'm still in school so the college schedule keeps me on my toes. Anyways, my typical load is one of the lowest pressure loads listed in the Alliant manual. Probably not the best load for these old guns, but it is right around 9000 psi if my memory serves me right. I don't have access to the manual right now, so I can't let y'all know what specific load it is.
FlyChamps, I do have an older gun than my fox, but probably not nearly as nice (or old) as your Lang, it's an Ithaca Lewis from 1903 that I shoot regularly with 7/8 oz. black powder loads. She performs beautifully with the loads that I have been shooting for the last couple months.