Just an FYI for those of you that have an 1858 and a conversion cylinder. I just ordered a couple, yeah, probably could have made them also. If I have this right you unscrew the loading lever, replace it with this spring loaded keeper. To swap the cylinder, you squeeze the keeper, pull the cylinder base pin out, roll out the cylinder. Put in the loaded cylinder, slide in the base pin, and release the spring loaded lever. Mine should be here in a few days I will let ya'll know if I got it wrong.
https://www.midwayusa.com/product/1973292517?pid=883599
According to the Midway ad: To load and reload a conversion cylinder you have to remove the cylinder from the frame each and every time. Save time and eliminate the hassle of the loading lever with the 1858 Remington Cylinder Pin Quick Release. Can be used in any 1858 Pietta or Uberti model frames.
Would also come in handy if you were shortening your barrel to make a snub nose 1858 or what I believe some call a bulldog.