"It seems that in reading on Fort Pillow, an officer commanding one of the assaulting regiments, who actually went over the parapet with his men, is quoted by Dr. Wyeth as stating that before the lunge into the works, each man had (as I recall, not having the reference at hand) "gun and navy six" cocked and ready to pour fire into the defenders. From previous posts I see that "guns" might be any description of shoulder arms, and I take "navy six" to be Colt Navy revolvers, cal .36."

I think that your recollection is correct. However, the term Navy Six is much broader than just the Colt model of Navy. Many manufacturer's had both "Army" and "Navy" versions. Navy mainly referred to any full-frame revolver of .36 caliber. Army referred to any full-frame of .44 Cal.

"This would suggest that the vast majority of those assaulting Fort Pillow each carried some long arm (I had assumed carbines, but probably not) AND a revolver, quite possibly the reworked pocket revolvers you described. In what calibre were the 1849 pocket revolvers orginally made, and to what were they reworked? Did these have six or five chambers in the cylinder? Might their similarity to the Colt Navy revolver have led to their being termed "navy six"s?"

The 1849 Pocket was .31 Cal., available in both five and six shot. Two models of Colt pocket were introduced in 1862 that were .36 Cal. One was called the Police and one was called the Pocket Navy. These were only available to the South by capture, as sales by Colt to the Confederate States had ended in late 1861. I have seen a handful that were Confederate used...origin unknown. Colt's official line to this day is that it never sold guns to the South after it left the Union. This statement is found to be untrue. Based on that untruth and other evidence, I leave open the possibility that Colt continued to supply the South with guns even after it became illegal.

There is a possibility that the 1849 Pockets were those guns sold by Colt to the Confederate States in 1861, then later reworked. However, the caliber was not altered.

"As I recall the Leech and Rigdon, and the Giswald and Gunnison revolvers, of Confederate maufacture, were cal .36. Of course, the Confederate ordance dpt tried to standardize cal .577 as that of all their rifle muskets, for obvious reasons, but might .36 have been chosen as the standard for revolver? I don't see much reference to Colt Army, cal .44, in Confederate hands."

Both the Leech and Rigdon, and the Leech (w/o Rigdon) are .36 Cal., based on the Colt Navy design. Griswald and Gunnison revolvers are .36 Cal. These two manufacturers supplied the largest number of Confederate made handguns. Almost all Confederate manufacturers used the Colt Navy as a basis of its designs. .36 is generally considered the Confederate handgun standard.

However, there were a number of other manufacturers (i.e. Dance Brothers; Tucker, Sherrod, & Co.; and Samuel Sutherland) who offered .44 Cal. models. A number of imports were also commonly purchased in .44 Cal. (i.e. Tranter and Kerr's Patent) which were really 12mm weapons.