If Colt made 1600 1851s in .44 caliber I would think that Flayderman's Guide would mention it. The fact that it doesn't does not mean that they didn't exist, but they would indeed be VERY rare guns and as his guide is aimed at collectors, I would think he would include it.
In speaking of the 3rd model Dragoon, he says it was sold both to civilians and the military from 1851 to 1861. This would be in the time frame mentioned above for the '51 .44 Cal Navy. Of course it had a round-back trigger guard and weighed about 4 pounds, but weight is no problem when the horse is carrying it, and the large powder charge it would take was very useful. It was popular with the Military.
He goes on to mention that these 3rd model guns had Silver Plated Trigger Guards when sold to Civilians, but the Military issue guns were plain.
I wonder if someone might have confused these 3rd model Dragoons with a 1851? From a distance, they do look similar unless they are right next to each other so the size diffrence is obvoius.
I wonder why a Calvary unit in this time frame would use a lighter, lower power gun instead of what the rest of the Calvary units were using? :: ::
My curiosity is roused. :: ::