i have machined them from copper bus bar before
just lathed the flange section and cut the hole to slightly under pipe size, heated them and let them shrink onto the pipe then solder
they did not have the "pipe" section like a ferrule they were just like a disc / ring
also did the same with SS ones
lathed them out to pipe size from flange side and then cut off the "pipe section" of the ferrule leaving a "disc"
heated onto pipe and soldered
or does US pipe slip inside the SS ferules anyway ?
thought it might be a option you can look into