The pictures of Henri Pieper's patent of his method of joining bbls is his US patent. Said patent was issued Aug 23, 1881 as US patent #246,195. This patent can be viewed here;
http://www.pat2pdf.org/patents/pat246195.pdf
A reading of this patent quite well describes the method of joining. The breech piece & bbls were stated to be turned with mating conical tapers & were further joined by either brazing or soldering. There were no threads in this patent. This did give the "Fretted" assembly.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra