John,

I can't recall any direct evidence of breech-loader equipped CS naval vessels by the time of the correspondence (although I wouldn't be surprised if there is some--I just can't think of any at the moment.) I did a quick search through Silverstone's "Civil War Navies" listings for the CSN vessels and didn't find any specifically listed as using these small caliber breech-loaders. The book does list various Armstrong stats in the intro ordnance section. It seems likely that some of the small gunboats did use the small caliber breech-loaders at times.

Some small Clay and Armstrong breech-loaders were imported but don't seem to have found favor with the CS army. However, they might have proved useful for the navy. Speculating: The naval vessels would have more access to mechanics and works to keep the unreliable mechanisms functional. Additionally, a CSN vessel would only need to fire them periodically and ideally could disengage. This would simplify supply (dependent on specialized imported ammunition) and make failure of the breech less problematic than for field batteries.

As for the scheme, muzzle loaders clearly wouldn't be practical for "canoe" mounting. Keep in mind that about half of the Whitworths were muzzle loaders. If one had to come up with a way to make such a scheme workable, the lightest and shortest possible breech loader would be the natural choice. The heavy canoe would need outriggers for stability.

I think watching some unfortunate crew trying to fire such a piece from a heavy canoe could be VERY entertaining. So perhaps he only intended the pieces be light enough to transport by canoe? (But if so, why the breech-loading requirement?)

There were already some very light cannon that could have served some of the purpose but were very light field weapons: 12 pdr mountain howitzer (range too short by comparison), CS mountain rifles and Hughes guns (both too diminutive for much substantial impact.) These could have been transported by canoe but would have lacked the sting and effective range of 6 and 12 pdr rifles.

Perhaps there was some use of small breech-loaders on small CSN launches that he was aware of and wanted to adapt to river use?