From the Napoleon Series Forum [by Steven H. Smith]:
“6) Skizze über das Militair des ehemaligen Könignigreichs Westphalen S. 55 [-80] und 433 [-466].” in Militairische Blätter. pt.1 (1823).
Seite 126 [-152] in Militairische Blätter. pt.2 (1823).
For more downloads, see the post at: http://www.napoleon-series.org/cgi-bin/forum/archive2012_config.pl?md=read;id=134044
Some of this same material is found, in French translation, in the Bulletin des sciences militaires: Huitième section du Bulletin ..., Vol. 3 (1826), pp. 1-20: https://books.google.com/books?id=inwDAAAAYAAJ&pg=PA1
Westphalian Artillery materials on-line:
“Westphalian "Brigade de reserve." ”: http://www.napoleon-series.org/cgi-bin/forum/archive2006_config.pl?md=read;id=53425
Westphalia artillery tubes:
Petrov lists, under Naples, 31 6 lb tubes and 9 howitzer tubes, each bearing the monogram ‘JN’. These pieces are in fact Westphalian.
Petrov’s attribution comes from the belief that the monogram ‘JN’ was that of Murat using Joachim-Napoleon as his throne name from 1808 to 1815. Murat, however, used the monogram ‘GN’ on his military equipment.
Jerome, Napoleon’s brother, used Hieronymus-Napoleon as his throne name but the monogram ‘JN’ on his military equipment. Interestingly, Westphalian coins bear the monogram ‘HN’, just to confuse the issue:
Some are dated 1810 (the information is very limited on separate pieces in the catalog) one has the weight ‘P 835 D’, others between 875 and 884, between the lifting handles. One piece is marked ‘20 p 35 fi’ and ‘884' this would suggest a pound of .3868 kg.
Petrov provides the following dimensions for the 6 lbers: bore: 3.7" (9.4 cm.)*; length from muzzle face to rear of base ring 57", 16 calibers long (144.8 cm.); weight 22.5 pud (368.5 kg.). It should be noted that only one set of measurements are provided for two different types of tubes. I believe these are for the 2nd type.
Several of the second type Westphalian 6 lbers were in the Swedish Army Museum collection (Armémuseum: http://www.sfhm.se/ArmeDefaultPage____27.aspx ). I viewed and photographed them many years ago.
This is a drawing of one of these pieces, dated 1812:
Weights marked on the left trunnion of these pieces ‘P 903' and ‘P 905'. The pieces are numbered on the right trunnions ‘No. 2' and ‘No 6' respectively.
I [Steven H. Smith] was not able to locate and photograph the Westphalian howitzer tubes in the Kremlin collection. Petrov provides the following measurements: bore diameter 6" (15.2 cm.); length from muzzle face to rear of base ring 40", (101.6 cm.); weight 18 pud (294.8 kg.).
(*) There is a misprint in Petrov’s text. The text states 6.7" which clearly should be 3.7".
“The only reference I have come accross for French using Russian guns is are 24 russian guns being used to equip the Westphalian artillery in December 1807 as stop gap meausre.”: http://www.napoleon-series.org/cgi-bin/forum/archive2006_config.pl?md=read;id=67615
“Westphalian Artillery in Spain”: http://www.napoleon-series.org/cgi-bin/forum/archive2007_config.pl?md=read;id=71162
“Friedrich Wilhelm Ernst Briede”: http://www.napoleon-series.org/cgi-bin/forum/archive2009_config.pl?md=read;id=102441
“Die Artillerie des Königreich Westphalen” (1,5 MB) : http://www.napoleon-online.de/Dokumente/Westphalen_ArtillerieKloeffler.pdf