Howdy Again
Yes, the Kopec book is spendy. I was lucky enough to find a used version a few years ago for a good price. It is a big, fat book, 600 pages long, and I have not read every page. I pick through the table of contents and the index to find what I want to know.
The design of the Colt Single Action Army was an evolutionary advance from the earlier Colt cap & ball revolvers and cartridge conversion revolvers.
Colt was prevented from building any cartridge revolvers by the Rollin White patent of about 1855 if I remember correctly. White had patented the idea of boring the chambers of a cylinder completely through the cylinder, so it could be loaded with metallic cartridges from the rear. White was a former Colt employee, which makes an interesting story for another time. S&W approached White and proposed buying the rights to his patent. White would not sell, but made S&W the sole licensee of his patent, making them the only US company that could legally make cartridge revolvers without being sued. So Colt was left making C&B revolvers all through the Civil War until the White patent expired.
Colt made a number of Cartridge Conversion revolvers during this period, principally the Thuer conversion, the Richards Conversion, and the Richards-Mason conversion. The Thuer conversion was an attempt to get around the White patent, but it used an unusual reverse tapered cartridge and was not financially successful. The Richards Conversion was financially successful, using some inventoried parts from the cap & ball revolvers and some newly manufactured parts. It fired a centerfire 44 caliber cartridge called the 44 Colt. The principal buyer of the Richards Conversion was the Army. The Richards-Mason Conversion simplified some of the parts of the earlier Richards Conversion and they too were financially successful. The Colt Model 1871-1872 Open Top revolver is often considered a cartridge conversion revolver, but in fact it was designed from the ground up to fire cartridges. It fired a rimfire 44 caliber cartridge very similar to the 44 Henry rimfire cartridge. The Open Top had been designed by William Mason, who had also made most of the changes that resulted in the Richards-Mason Conversion. Except for a few internal parts, all of the parts of the Open Top were of new design and very few parts were interchangeable with cap & ball or cartridge conversion parts.
The patents for the Open Top were awarded in 1871 and 1872, but Mason was probably working on it earlier than that. The White patent had expired in 1869, so the market was wide open for a large caliber cartridge revolver, unlike the small Tip Up rimfire cartridge revolvers S&W had been producing. The largest Tip Ups only fired a 32 rimfire cartridge. S&W was ready in 1869 with a much larger revolver, but that too is another story.
Mason was working on the design of the Open Top concurrently with developing the Richards-Mason cartridge conversion revolver. Among other improvements it featured a hinged loading gate and an improved ejector assembly. Colt submitted the Open Top to the Army for consideration as a new cartridge revolver design, but the army rejected it. One reference of mine states the Army had decided on a solid frame revolver as early as 1868, but Colt submitted the Open Top anyway, and it was quickly rejected.
Mason had also been working on what we now know as the Single Action Army early in 1872. It was often referred to as the 'Strap Pistol' by both the Army and Colt, to differentiate it from the 'strapless' (my term) Open Top. The Army stated they wanted a solid frame revolver, with a threaded barrel screwed into the frame. Colt sent the first Strap Pistol to the Army in November of 1872. The Army tested it in comparison with the Smith and Wesson American Model that was already in inventory, the Army had bought 1000 of them around 1871 if memory serves. The first Strap Pistol that Colt sent to the Army was chambered for the 44 Russian cartridge, because it was felt to be more accurate than the earlier 44 S&W American cartridge. However since the Army's American Models were all chambered for the S&W American cartridge, this first revolver was sent back to Colt to be fitted with a cylinder chambered for the 44 S&W American cartridge.
My point is that there were several variations of the SAA that Colt sent to the Army for testing, each variation being suggested by either Colt, or the Army, or both.
For reference, here is a photo of an Open Top.
Here is a 2nd Gen Colt Single Action Army.
