Howdy
Fist, let's clear up the story with the six shot R&D 45 Colt cylinder for the 1858 Remington. The cylinder for the 1858 Remington is not large enough to house six 45 Colt chambers without the rims overlapping. So Ken Howell took out a patent with the chambers angled out ever so slightly towards the rear, so there would be room for six 45 Colt cartridges to chamber without the rims overlapping. Howell was selling these under the name R&D and Taylor's and Company was the sole distributor. Yes, other companies were selling them, but they were buying them from Taylor's.
Here is a photo of my six chamber 45 Colt R&D cylinder and its backing plate along with my old EuroArms Remington. To those who think it is silly to spend the money to convert a BP revolver to cartridges, I bought this revolver back around 1975, so I had it for so long that by buying the cylinder for around $200, which is what they cost when I bought it around 20 years ago, it was like I was buying a new cartridge revolver for $200.
At some point Howell sold the rights to his patent to Taylor's, and Taylor's has been selling these cylinders all along, although they have contracted with someone else to make them. They are still available from Taylor's.
https://taylorsfirearms.com/accessories/conversion-cylinders/1858-remington.html
So when Ken Howell first set up his own company to sell conversion cylinders for Cap & Ball revolvers, he was prevented from selling a six shot conversion cylinder for the 1858 Remington chambered for 45 Colt by his own patent, that he no longer owned the rights to. He sold all kinds of conversion cylinders, just not a six shot 45 Colt cylinder for the 1858 Remington. Howell is now selling such a cylinder, so I can only assume his patent has run out. Patents do not last forever, they can be renewed, but unlike Trademarks they do have a shelf life.
And before anybody gets upset about a cylinder with angled chambers, I can tell you the angle is so slight it does not affect the performance of the revolver at all, my 1858 Remington with its 45 Colt cylinder is the most accurate 45 Colt revolver I own, and I own quite a few.
Back to the question at hand. Here is the pamphlet that came with my R&D cylinders (I actually have two of them, one for my EuroArms Remington, and another that came along with an Uberti Remington that I bought used a long time ago.
I have already had my hand preemptively slapped about pressure and 1000fps, so I won't go there. Suffice it to say, there is no recognized SAAMI Maximum pressure standard for 45 Colt Cowboy ammunition. It is what ever the manufacturer chooses to be. I tend to doubt that most commercial Cowboy Ammo is a whole lot below the 14,000psi Maximum pressure that SAAAMI recommends. I know some Cowboy Action shooters who load their 45s down to ridiculous levels, to recoil about like a light 38 Special, but that is the stuff they hand load themselves.
Personally, I only ever shoot ammo loaded with real Black Powder out of my Remingtons with their conversion cylinders. My standard 45 Colt load is 2.2CC of Schuetzen FFg under a 250 grain Big Lube PRS bullet. I do not add any filler, I compress the powder between 1/16" and 1/8" when I seat the bullet. A word about Black Powder here. Notice I am using an actual recognized volumetric unit, Cubic Centimeters. That is how Lee Dippers are calibrated. A CC is the same as a milliliter. Different Black Powders actually weigh different amounts. 2.2CC of Schuetzen FFg comes to about 33.3 grains, which is all that can be added to modern solid head 45 Colt brass without compressing the powder a whole lot more. The only chronograph data I have on my BP 45 Colt loads is 2.2CC of Goex FFg (about 31.3 grains) was propelling the same 250 grain bullet at an average of 704 fps. That may sound slow, but it is a handful in a revolver. This photo shows the components of my 45s, but I actually load them on a Hornady Lock and Load progressive press.
Although I regularly shoot those loads in a Colt, I found the recoil to be a little bit punishing with the different grip shape of a Remington. Also, I was concerned about the strength of the frame where the loading lever pierces through the frame. The walls of the frame around the loading lever are pretty thin right there.
I did not see any actual deformation of the frame with my Black Powder 45 Colt loads, but the only Big Lube bullet available at the time was the 250 grain PRS bullet. I wanted to go for a little bit less recoil, so I designed a 200 grain Big Lube bullet for my Remington. It is called the Big Lube J/P 45-200 and molds are available from Big Lube. No I do not receive a penny from this, I created this bullet as a service to the Black Powder cartridge community.
http://www.biglube.com/
To further reduce recoil, I began loading 45 Schofield brass, which is shorter than 45 Colt and does not hold as much powder, with Black Powder and the J/P 45-200 bullet. I load 1.9CC (about 28.5 grains) of Schuetzen FFg in these rounds. Sorry, I have no chronograph data on these loads, but they produce plenty of smoke and are very pleasant to shoot.
As I said, I only shoot cartridges loaded with real Black Powder in my Remingtons with their conversion cylinders. I have not loaded 45 Colt with Smokeless in a long time. When I did, my standard load was 7.5 grains of Unique under a 250 grain hard cast lead bullet. My loading notebook says these were doing about 800fps out of the 7 1/2" barrel of a Ruger 'original model' Vaquero. I have no pressure data on that load. My old Speer #13 loading manual gives the acceptable range of Unique for this bullet as 8.6 grains to 9.5 grains MAX. I think those loads are a little bit hot, but Speer states they are under 14,000psi. The only pressure data I have for Unique with a 250 grain bullet is from Richard Lee. Lee tends to be conservative with his data. He states both the starting load, and the MAX load for a 250 grain bullet with Unique is 8 grains, which delivers 850 fps. This is pretty much the standard Unique load for 45 Colt. Others will say you can go higher than 8 grains of Unique, Lee says not to. Anyway the pressure for this load is 11,800 CUP. Sorry, I do not have a conversion formula for CUP to PSI, I think it is a bit more complicated than we think.
Anyway, if I was going to shoot Smokeless from my Remingtons, with their conversion cylinders, I would probably start with a bit less than 7.5 grains of Unique and maybe a 200 grain bullet.
Just guesswork on my part, please do not take me to court if you blow up your conversion cylinder. Please consult an actual printed loading manual, do not follow advice you get on the internet, including this advice.
P.S. I guess I am behind the times. I have a copy of Lyman's Cast Bullet Handbook, 3rd Edition, copyright 1980. Several different powders listed for a 250 grain cast bullet, including Unique. Includes minimum and maximum velocities. No pressure data. Everything is below 1000 fps, but their MAX charge for 45 Colt and Unique is 875 fps. No, I ain't gonna quote the amount, buy the book. I doubt if the data in the 4th Edition has changed much from the 3rd Edition.
