Time to update this thread:
I actually got a phone call from USFA a couple of days ago(!). The smith who's working on my guns apologized for taking so long, said he was in a head-on collision 4 months ago and is only now getting back to work. Which would explain a lot about the time taken to repair our guns. But as my wife pointed out: "why didn't they tell you that 3 or 4 months ago?"
I reckon most of you .44WCF owners/shooters know about the issues concerning bore/cylinder/chamber/throat diameter differences and problems. (the dimensions vary wildly depending upon who made it and when).
Unfortunately, it seems that .44-40 brass has a pretty wide range of rim thicknesses, too, according to the smith at USFA. My starline shells are on the thin side, and the guns headspace at .011 or .012, which is out of spec. But WW brass with a couple of thousandths thicker rims headspaces correctly....
The smith called an expert on black powder (a gun writer with decades of experience) and he suggested that I should open the primer flash hole. Which was an early suggestion in this thread. And which would cause some headaches 'cause I load both smokeless (sorry
) and black powder, and the altered brass would only be good fer b.p.
The USFA smith is going to play around with a magnum recoil shield and firing pin. Hopefully I'll get the guns back before 2010. Then I'll update this thread with a range report.