Also, I'd have to see some verification of the Walker originally being set up as a carbine with a .54 calibre ball. According to my information, it was always intended as a six-shot hand gun using a .44 calibre 220 grain "elongated ball".
The Walker being originally planned as a 53 caliber is a known fact not in dispute among serious students of Colt C&B Firearms.
Look at the breech end of the Walker barrel and you will note that the barrel is actually bored off center with the bore inclined upwards till it comes out centered at the muzzle.
This was because Colt had already set up the machinery for the .53 Barrel blanks before abandoning the .53 caliber idea for a more sensible .44 caliber.
Ive seen detailed sketches of the rebated cylinder .53 action.
As I said the .53 design is well known among Colt firearms researchers. Not so well known that everyone who collects the Colts knows about it though.
.54 caliber horse pistols and single shot pistol carbines were a standard issue before the Colts caught on.
Whether it was developed from a carbine design or not is my own speculation based on anomalies of the Walker's grip design, and the fact that Patterson Carbines were already in use with the US Army at the time.
The action size and the scallop cut in the frame look more suitable for a carbine.
Walker wanted a powerful .44 Caliber revolver as quickly as possible and Colt adapted parts of the .53 experimental to the job.
Problems with the early Colt metalurgy made even the Walker dangerous at times. Many ended up with cracked cylinders or barrel. A .53 gun would have been an accident waiting to happen.
Colt later obtained rights to a Molybdenum alloy meant for leaf spring and built his large caliber revolvers from this new "Colt Silver Spring Steel" from then on.
PS
Here is a .54 revolver Carbine buit by a competitor . I expect that a .53 Colt Carbine would have been similar in proportions and deployed in the same manner as his Patterson Carbines.
The Paterson carbines were overly complicated and expensive so an improved carbine built on the Colt redesign would have been welcomed by the military at the time.
http://airbornecombatengineer.typepad.com/airborne_combat_engineer/2006/09/rare_1853_revol.html
PPS
Took a quick run through of available information on the net.
All I've found so far is that Blunt&Symes built the first Walker Prototype for Colt and theres a surviving prototype barrel which has no loading lever, being meant to be loaded using a hand held rod with palm rest, like the Trapper Colt 36.
The best Colt reference book at our local library was vandalized by some yahoo with a razor who cut out dozens of photos of the rare Colts found there. I don't know where I could find any information on the prototypes locally.
I'll Check my old American Rifleman Magazines later, perhaps theres an article in one of those.