Howdy
Granted, the economics of buying a Cap & Ball 1858 and then buying a conversion cylinder for it are not as good as buying a cartridge cylinder in the first place.
In my case, I bought this EuroArms Remmie back in 1975, and I haven't a clue what I paid for it back then. Of course conversion cylinders were not available back then. When I became aware of them around ten years ago I figured for $200 (they cost then) I would be adding a new cartridge gun to my collection for not very much money. I thought it would be great to be shooting cartridges in the old Remmie and I figured the old C&B had paid for itself a long time ago.
Then a year or two later I came across a used Uberti Stainless Remmie complete with a conversion cylinder for about the price of a used cartridge revolver. A no brainer for me.
These cylinders are the old six shot, 45 Colt cylinders that Ken Howell was producing for Taylors. It is not physically possible to fit six 45 Colt chambers in the cylinder for the 1858 Remington without the rims overlapping. So Ken had the brilliant idea of angling the chambers out ever so slightly, less than 1/2 of one degree, so six chambers could fit without the rims overlapping. And he patented the idea. At some point, Taylors bought the patent from Ken, the cylinders they are selling today are produced by somebody else. So when Ken Howell started his Old West Conversions company to produce conversion cylinders, he could not use the idea he patented because he sold the patent. That is why all of his 45 Colt cylinders for the 1858 Remington are only five shots.
This type of cylinder does require removing it every time you reload because there is no provision for a loading gate with the arrangement of the cylinder cap. Kirst makes a cylinder that has a backing piece bolted to the frame with just one firing pin. This allows one the option of carving a loading gate into the frame. However removing the cylinder is so easy on the 1858 model that it is probably quicker to reload this way than popping the empties out and reloading one chamber at a time through a loading gate.
Now, having said all that, since this is a Black Powder forum, it must be said that the 1858 Remington suffered from a design problem that made it less than perfect for shooting with Black Powder. The cylinder lacked any sort of gas bushing or collar on the front face of the cylinder.
This resulted in the barrel/cylinder gap being directly in line with the front of the cylinder. Because of this, BP fouling blasted out of the gap was deposited directly onto the cylinder pin, where it worked its way onto the cylinder pin, causing the cylinder to bind with BP fouling. With the conversion cylinder the situation is the same and fouling is rapidly deposited on the cylinder pin.
Which is another reason I prefer this design of conversion cylinder. Every time I remove the cylinder to reload, I wipe the cylinder face off with a damp rag and wipe off the cylinder pin. This allows the gun to keep shooting longer without binding up.
Incidentally, this is the same reason the modern reproductions of the Schofields do badly with Black Powder. In order to chamber the conversions for cartridges longer than the original 45 Schofield round, cartridges such as 45 Colt and 44-40, the cylinders had to be lengthened to accommodate the longer cartridges. But the frame was not stretched a proportionate amount. Instead, the gas bushing at the front of the cylinder was shortened, providing less of a shield for the arbor from BP fouling blasted out of the barrel/cylinder gap.
The original Smith and Wesson Schofield did fine with Black Powder. It had a substantial gas collar pressed into the front of the cylinder.
The gas collar slid over the cylinder arbor.
When the cylinder was pushed all the way forward, the gas bushing protected the arbor from fouling blasted out of the barrel/cylinder gap. This arrangement was the same on all the old S&W Top Break revolvers.
Regarding the 1875 Remington design; Remington learned their lesson and did provide a bushing on the front of the cylinder. But it is not as substantial as the bushing on the front of a Colt or colt clone. At least not with the replicas I have examined. While the 1875 design does provide protection against fouling being blasted onto the cylinder pin, nothing does as good a job to keep the cylinder rolling with modern reproductions and Black Powder as a Colt or colt clone. Rugers work very well with Black Powder too.