I know this is an old post. But the cylinder is for an 1858 Remington. Don't remember who, either Howell's or Taylors has a stamp with a P or U for Pietta or Uberti designation. I had one and it would chamber a 357 cartridge. The bullet would stick out a little. But a wadcutter seated deeper would work. I loaded it with Trail Boss and it worked just fine.