Chuck,

It is possible that there were more than one type of Hughes guns. This one, I think is a later version under the 1863 patent. The 1861 guns seem to be smaller a lighter peices built on light carriage wheels. Some info on these in an article on the Co. of Military historians site.

It is possible that your gun was rifled at one time and reamed. There appears to be some light rifling markes on top about half way down the bore.

It is unfortunate that the percussion lock is missing, whatever was attached to the bottom comming up by the locking lugs.(a safty of sorts I am sure.)

There are several article's in the Confederate Vet's Mag.
Look in 1907.08 10 and 29.

A neat gun for sure.

It shot a regular minnie ball(enlarged) and 15 minnie balls (58 types) for canister.