You provide maximum ranges at elevations of 6 to 6.5 degrees, presumably drawn from published range tables. This is a far cry from 45 degrees. I note the superior results of the An XI versus Gribaeauval pieces in this test.
"The field guns could fire up to 10 degrees elevation and record a hit on the target." ... To make sure I understand this correctly, you are stating that the guns could and did fire at a higher elevation than the howitzers. If the guns could fire and hit at 10 degrees elevation, is this the maximum elevation the carriage permitted, or the maximum elevation at which hits were obtained? What was the maximum elevation for howitzers in An XI and Gribeauval systems? I would like to understand if the howitzer carriages imposed a lower elevation than the gun carriages.
"Beyond 15degrees elevation the howitzer axles did not last the 100 rounds." ... that seems completely reasonable to me. The horizontal vector component of the recoil was absorbed through two mechanisms: (1) pushing the gun and carriage to the rear, with the propellant driving a 6-12 mass in one direction and a
mass two orders of magnitude higher in the opposite direction; and (2) friction from the axle (minimized by lubrication) and from the trail (maximized by design without adversely affecting stability). The vertical component had nothing to absorb the force.
Alexander - do not worry about misleading me. I may have misunderstood you, or we may not yet be communicating clearly. It seems to me that there is some confusion either within the primary material or within our reading of it. Scharnhorst states 45 degrees, I wonder at the carriage being able to absorb that stress, Paul states that the carriage was neither designed to fire at that angle nor could it hold together for long under that stress. Something is not adding up yet. I am intrigued by your quotes about French howtzers outranging Russian guns, and would like to clarify if this was an apples-to-apples comparison, or if the French possessed a tactical advantage from terrain, or if the French and Russian pieces were of significantly unequal calibre.